I think most people are angry at the fact that developers aren't really giving an effort with the Wii, graphics wise. I can't think of one third party developed game that pushes the Wii hardware. Nintendo has done it at least twice, maybe three times already. It isn't a huge leap forware from last gen, and i've yet to see an Wii game look better than the top of the crop of the original Xbox, but it's still a jump from the Gamecube.
There are however people on this site that look at stillshots of future games for the Wii that look very impressive and don't see it's not going to look that good in motion. They'll make comments that they swear it's PS3/360 quality and sound foolish even bring that up. Then we have the same crowd that sees a mediocre looking 360/PS3 title in screenshots and swear it could be done just like that on the Wii. Again, straight foolishness.
I think most people here are levelheaded and understand that the Wii is in another category graphics-wise from the PS3 and 360, and should probably be directly compared to the Xbox to judge quality.