Just don't like them, I think the main issue for me are the controllers. I cannot use them with the dexterity and speed I have using a mouse and keyboard. So I get frustrated with myself because I know I'm a better gamer than the consoles controls let me be.
I have a fairly well specced PC and I see the limitations in what are now 2nd/3rd generation graphics architecture in the PS3 and XBox360.
Also, I find a lot of PC games have more depth to them than can be found in a lot of console games.
Not taking a bash at console gamers at all, but it is just not for me.