Surface
The top coating looks and feels exactly the same as on the Iris Optical RGB and Ventus X Optical (and also some Cougar mice, like the Minos X5 and Revenger S). It can be described as a transition between a glossy and matte finish—it's not very grippy, but isn't quite slippery either. The best part is that it really doesn't collect fingerprints at all and gets grimy way later than some other finishes I have tried so far, and since there is no rubberization, there is no chance of it flaking off after a few months or years of use.
The side panels and thumb rest feature a smoother coating than the top. Both the left and upper part of the right side have some minor texturing for a more grippy surface. On the left side, you probably won't really touch the panels themselves because the side buttons are designed to be the main gripping area there.
Build Quality
I have found the build quality to be perfect with one exception. Unfortunately, the scroll wheel can wobble and rattle around in its spot. This only happened when I tried to tilt it sideways or when I shook the mouse rather vehemently. I did not encounter the issue while playing or just generally browsing and scrolling with it. With 1–2 fast swipes, it can occur, however, but only if your fingers don't touch the scroll wheel itself. Anything else is absolutely fine; no scratchy mouse feet, no creaking or squeaking shell, and everything else is firmly in place.
Weight
The Nemesis weighs about 112 grams with a few centimeters of cable. The downside of the side button mechanism is that it causes the mouse to be quite heavy for its size, and the weight is a bit unevenly distributed to the left. If you don't lift your mouse much, it should not be a problem, but generally, lighter mice are better for your wrists over the long term.