first time i've seen an FPS done properly on a handheld for sure...
one thing i've always hated about console FPS's is the generally restricted plane of action. it's either that or trying to aim with one analog stick and move with the other, which coming from a PC just feels retarded.
hand cramp issues aside (i had some pain but that was after two 2-hour sessions) i found using the touchscreen to look around quite intuitive.
sure story~, explorey, and environmenty~wise it doesn't quite stack up to Half-Life, but like the reviews say the single player game is fairly solid, and what most of the reviews didn't mention is that you can play any of the multiplayer levels against bots, which is great for practice and a quick shooty-shoot fest.
i'm happy with it, tbh i wanted at least just one game that looked pretty and consisted of not much but run and shoot stuff... after a hard days animal crossing and fire emblemming sometimes i need a change of pace! there's some backtracking, but not so annoying, a minor trek back might uncover a whole section as big again as the "normal" part of the level, which is cool.