While Crysis Warhead tries to innovate with a more cinematic, carefully-sculpted experience and tosses in a couple of new weapons (and a hovercraft, which is severely underwhelming) and more multiplayer action for a reasonable $30 price tag - either in stores or over Steam - it's not enough to fix the problems of the original game, nor does it take advantage of Crytek's strongest gameplay of years past. The system requirements are still rough, the freeform combat has been minimized, and the experience is pretty short if you aren't going to be getting into the online play too much.
And the weirdest thing? Crysis Warhead's single player game doesn't have any actual warheads or nukes. Hell, the original had that tac nuke cannon that was grossly underused but still at least present, but there are no nukes here. Odd. Either way, it's worth picking up if you really dug the original and want more of the same, but if you had issues before, then Warhead isn't likely to address them for you.