Okay Ive played for a while now. The performance on Enthusiast is a lot smoother on my card at 1680*1050 than on Very High in Crysis. Its almost playable.
BUT it is clear that the graphical quality is lower. Draw distance is noticable worse than in Crysis (Very High) and I think the textures are worse. The draw distance is particularly annoying as when you walk on a path, you can see rocks on the ground appearing in front of you. This is for stuff which is only about 20m in front of you. If this is how they "optimised" crysis then I am hugely disappointed. In addition, you lose the beautiful cliff faces. They arent as good in warhead.
Also, I don't want to install Gamespy Arcade dammit. How do you prevent it prompting you about it all the time? This is for Crysis Warhead, I havent got round to downloading Crysis Wars yet. In addition, why does it install Punkbuster for Warhead? I've uninstalled that already. If Crysis Wars requires it, then it can install it on its own. I don't need 2 punkbuster services running for no reason whatsoever.
edit: draw distance can be fixed by editing the cfg files in the cvar directory. I've done that with help from someone on another forum and performance is very similar to the original crysis now.