Got it on release day, beaten it a few times now, it is freaking awesome. I HIGHLY reccomend it, even if you don't have the first Crysis, its just that good. The graphics are amazing, there is some more variety in the aliens you encounter, you get to fight more nanosuit Koreans, you get a couple of new weapon options that are very handy.
Still testing it now but custom CVars seem to work in Warhead, so im sure the community will be awash with custom warhead configs soon enough.
The DRM... not as draconian as Spore, with Warhead you have unlimited installs on up to 5 different rigs, that I can accept. Once you verify online on install you DON'T need the game disc anymore, which is nice.
The Bad- It's too short, I want more! but you get that with a 30 dollar pseudo expansion. However the varying levels of difficulty are just that, varied. Normal seemed iddiot easy while Hard was quite a challange and Delta I'm still working through.
You do need a monster system to really enjoy it, The framerates seem improved over the first, but you still need a card in the 8800 range and preferebly better to really go at it.
Purchace Warhead and support Crytek, they are showing what the future of PC gaming can and should be... IF they don't abandon it and go to the consol systems. I hope enough folks will buy Warhead so they stay with the PC.
KP