I do hope most people realize that cartoony games are the best candidates for simply rendering at a higher resolution and with better AA/filtering and come out beautiful. There's no fine detail to worry about. Wind Waker, Zack and Wiki, and Red Steel looks gorgeous for sure, but most detailed GC/Wii games like Twilight Princess and others -- while still looking a lot better compared to their original low res, little AA and filtering offerings -- still fall behind todays standards graphics wise.
Having said that, I am really enjoying playing GC/Wii/PS2 games in HD with great AA and texture filtering. Wind Waker has such a beautiful art style and the cartoony look just makes it a perfect upgrade. Looks fantastic.
The Wii just isn't for me only because I want the high(er) resolution textures, better AA, filtering, shaders and screen resolution. I also feel all developers on PS3/360 should make image quality their #1 priority. Take any HD game and take away the AA and it looks horrendous. That new Ninja Theory game is looking really bad at the moment because the screenshots they are releasing makes it look like the game has no AA. Art direction looks fine.
A gorgeous game is so easily ruined by bad AA and filtering. PC gaming is great but obviously very expensive and can be cumbersome when upgrading. But still very happy to have it so I can run PS2, GC and Wii games in HD!