Even with infinite ammo the game still sucks, only now it's just barely bearable. The character sucks at aiming (even worse than Sam Fisher, which is impressive), and the suppressed pistol sucks as well, shoots slow, and only has 7 shots.
This just isn't a good game. The stealth elements are inconsistent and flat out broken at times.
Now that I think about it, I don't believe that any stealth game can succeed without nonlinear movement, meaning restriction to just flat surfaces (the ground). Unlike a FPS, you can't rely on your weapons or health to brute force a situation linearly. You've got to rely much more on the environment, which means more movement and interactivity:
Thief, Splinter Cell, Riddick: you could climb, hang, drop down on enemies, neutralize light sources, whistle, throw stuff, etc. With this game you can only neutralize very few light sources, whistle (which causes enemies to RUN to your location), and you can't do any of the rest. You're simply limited to shadow areas in an otherwise linear path. Combine this with weapons that suck, sneaking that's too slow, and ineffective melee, and you've got a failed stealth combo.