Snake? Snaaaaaaaaaaaaaaaaaaaaake!
Ok first off the angle of the camera is awkward (3/4 isometric view? Who uses that anymore?) and makes moving around the grid harder than it has to, at least until you get used to it, which leads to needless fission mailures (sorry I couldn't resist :P ). Secondly, there is one level (about 8 or 9 levels in IIRC) that is IMPOSSIBLE to beat. Level design + the guard never moving away + no kill objective = no way to get through unnoticed = no way to win. At this point is probably a false hope, but it should be addressed... Speaking of which, level design is hit-or-miss, often either uninspired or nonsensical (4 guards in an empty room? Really?), but a few levels are well-made (the grassy one was really cool).
On to the good: graphics are nice, animation is smooth, and as mentioned, sticks true to the essence of its obvious inspiration. Really feels like a Metal Gear game, despite its odd quirks (like the grid system); has potential if the level design and the camera angle is improved.