The reasons i think people are complaining about the graphical side of things are all based on the legacy that the first crysis game created for itself.
Crysis 1 was the epitomy of showing the PC’s ‘superiority’, it gave peole bragging rights if they could run it at a playable framerate (or even at all) back in the day, and i think the fans of the first game were expecting the second game to keep this legacy alive, they were expecting the greatest pc game (in terms of graphics) ever made, and so to find out that the game won’t even be taking advantage of the latest graphics technology on release, or even let you change the game’s settings without having to delve into a config file is a massive let down.
I think it’s great that the game has obviously been optimised a fair bit so it can run well on some more lower end cards, but equally i think it’s quite obvious to see why the majority of pc players are so unhappy with it.
In short, i think in Crysis 2’s case graphics are something to be complained about.