Heres why I wasn't impressed at first. I only used it for a few minutes on each side, which resulted in nothing. I watched a video online with a master chef using his stone, and he sharpened his knife for 10 minutes on each stone before moving up to a finer grit. I took this hint, and used sharpened my knife on each side of this stone for 10 minutes, which led to perfection. 

A: That depends almost entirely on how often you use them. If you are a professional chef who uses his or her knives every day then you should hone them every time you use your knives. But honing has its limits and over time your edge is going to become dull no matter what. Therefore your knives will need to be sharpened at least several times a year. Some chefs, in fact, will use a whetstone on an almost daily basis in order to ensure their knives are always razor sharp. Most of us, however, are not professional chefs and may not even touch our kitchen knives for days at a time. In that case, it’s probably a good idea to hone the edge after every couple of uses and have your knives sharpened once a year.
I really liked this whetstone! I had a Smith's pocket sharpener that could get my knife sharp enough for working around in the yard (I have an Opinel no.8). However, in doing a little research I found that the sharpener was only around 600 grit on the finest setting. So this BearMoo 1000/4000 grit looked like the perfect step up, and it turned out to be the perfect stone for me. The pictures are an accurate representation of what you get. The removable rubber base was helpful when switching from one side to the next, and it kept the stone from sliding around. The instructions say that the stone can work with either water or oil, but that water is preferred. It said to leave the stone soaking in water for five minutes, and the stone worked like a champ. I especially liked how the instructions gave you an approximate time of how long the stone takes to sharpen a knife -- it just helped give me an idea that it would take about 15-20 minutes on the 1000 grit side, and then another 10-15 minutes on the 4000 grit. Just turn on a TV show!
For instance, American Novaculite (aka Washita and Arkansas Stones) is a form of metamorphic Chert that produces some of the best known and best loved natural whetstones in existence. Then, there is a form of Belgian Coticule which has been known for providing extra-keen edges since Roman times and, there is a Japanese Siliciclastic sedimentary stone (aka Japanese Water Stones) which consist of a fine silicate particles suspended in a clay matrix. Plus, there are also various types of man-made whetstones available such as Silicon Carbide (aka Crystalon) stones and Aluminum Oxide (aka India Stones) as well as a synthetic Corundum (aka Ruby) rod and Aluminum Oxide impregnated ceramic rods as well as several different types of diamond hones.
Table mounted device – Typically the manual powered table mounted sharpener looks virtually identical to the electric powered sharpener with a slot for each stage. Where they differ is that each slot in the manual powered sharpener has only one groove and you pull the blade through this groove toward you to sharpen the blade. Once the blade is sufficiently sharp you place it in the honing groove to refine the edge and pull it toward you again several times. If there is a third, cleaning, stage you repeat the process for that stage as well.
I like the fact that there are two different grits (can be seen as two colors). the black rubber feet stick to the kitchen granite top like glue. The 1000 does a pretty good job of getting a knife roughly there and the 4000 puts on a fine polish for razor a sharp edge. I would go the extra step of stropping the knife after the grinding operation for an extra sharp edge.
I recommend it as a lightweight alternative to larger stone for smaller knives. Leather necklace is comfortable and seems strong. I conditioned it for suppleness and swim with it on tightened as a choker. Stone is small, dog-tag size. I use it with water. Functional for small folder knives and multi-tools. Not useful for large fixed blades, since you can't make a long stroke. Small to grip. I use double-sided tape on one side to keep it in place on a flat rock. Not sure of grit, seems like around 1000. It took a while, but i got my old boy scout knife sharp.
At age 10, Terada learned the basics of sushi from his father and then went on to attend RKC Chef's School in Kochi, Japan from 1987-1989. He soon earned a nickname for his fast knife, attention to detail, divine presentation and ability to create new dishes and accents based on traditional Japanese cuisine. After graduating RKC Chef School, he was called to serve under Master Chef Kondo at Yuzuan restaurant in Kochi, Japan from 1989-1992. Mr. Kondo is the master of Kansai style cooking, considered to be the high-end of Japanese cuisine. Terada earned the title Master Sushi Chef by becoming the standing head sushi chef & can serve Fugu (Japan Licensed) to the public.
The angle on a Buck Knife is set based upon how we feel the knife will be used. Heavy use needs a strong and blunt "V" while skinning or filleting would need a deeper but more vulnerable "V". We tend to grind to 13-16 degrees per side (see illustrations). If you match the existing edge angle and hold the knife against the stone to cut evenly across the edge grind, you will produce an edge with a similar angle.

The word “Novaculite” is derived from the Latin word “novacula”, which means “razor stone” and is essentially a metamorphic, recrystallized, variety of Chert composed mostly of microcrystalline quartz that is found in the found in the Ouachita Mountains of Arkansas and Oklahoma and in the Marathon Uplift of  Deposited in the Devonian Period and the early Mississippian Subperiod some 410 to 325 million years ago and subjected to uplift and folding during the Ouachita orogeny of the Atokan Epoch (early Pennsylvanian Subperiod), Novaculite is a very tough stone that is resistant to erosion and thus, the various layers of Novaculite stand out as ridges in the Ouachita Mountains. Thus, due to both its availability and its composition, it has been mined since ancient times for use as arrowheads and spear heads as well as in more modern times for use as sharpening stones.
To summarize, Shapton Glass 500, 1,000 and 2,000 is a good combination and if you would like to throw in the 4,000 grit stone in lieu of the 2,000 that is good as well. If your knives are very hard, ZDP 189 for example, this is a fantastic choice. (They are also excellent for tools, chisels etc. and they are the premier choice for many Straight Razor honers).

I bought this and Unimi's 600/1000 whetstone at the same time. Curiously, reviews are currently blocked for their 600/1000 model, as amazon wouldn't let me leave one for it. Considering the conspicuous absence of reviews in the other stone's listing, one can only assume they're being censored for everyone. So, maybe I should be more critical of these stones, and use them a while longer before giving them any praise? But I've had a very positive experience with them so far, and the 600/1000 stone was the one I found most useful.
Ease of use – Most people in search of a mechanical sharpener want one because they don’t want to be bothered with trying to achieve a perfect edge themselves using a stick or sharpening stone. They want predictable, first class results every time. In that case it’s important that the electric powered device is easy to use, achieves results quickly and with little effort and is designed with user safety in mind. Keep in mind too that it’s easy to apply too much pressure when using a mechanical sharpener and when that happens you’re likely to see unsatisfactory results. In addition there are subtle differences between mechanical devices designed for Asian-style knives and those designed for Western-style knives. This has to do with the sharpening angle discussed above. Don’t get an Asian sharpener if you don’t need precise control over your cuts.
I've been using these stones for the past day, and they work great. Once you get the technique down that works for you, you can sharpen any knife to the point it can cut through news paper. Tip: make sure you count the amount of times you pass through the stone on one side and do that same amount on the other side. What I usually do is if I know the knife is very dull or chipped, I do 100 passes on each side using the 400 grit. I test the blade on thick paper and if it cuts through I test it on news paper. If it doesn't cut through the news paper I do another 50 passes on each side. Repeat this until the blade can cut through newspaper. After, on the 1000,3000, and then the 8000 grit stone I do 50 passes on each side. This should make the blade very smoothe cutting and polish it. I plan on getting a strop or piece of leather to further polish the blade. The only thing I don't like about this is that this package is that it does not come with a dressing stone so you can re flatten/level the stone after using them.
I recommend keeping two stones in your kit. One with a medium grit (around 800 or so) to perform major sharpening jobs, and one with a fine grit (at least 2,000) to tune the edge to a razor-sharp finish. For real pros, a stone with an ultra-fine grit (8,000 and above) will leave a mirror-like finish on your blade, but most cooks won't notice the difference in terms of cutting ability.

J. Kenji López-Alt is the Chief Culinary Advisor of Serious Eats, and author of the James Beard Award-nominated column The Food Lab, where he unravels the science of home cooking. A restaurant-trained chef and former Editor at Cook's Illustrated magazine, his first book, The Food Lab: Better Home Cooking Through Science is a New York Times Best-Seller, the recipient of a James Beard Award, and was named Cookbook of the Year in 2015 by the International Association of Culinary Professionals.