The graphics in games still look good, I've also notice that game that don't have AA seem to benefit on SDtv....mainly cuz the console still renders a HD image and then downscales it to SD but in doing so it give an affect like AA, so in some cases games look more jaggie on a HDTV than an SD.
The only real concern is the text, some games the text doesn't scale and it's hard to read, you also lose some peripheral vision, and the screen may some times feel a little cluttered, well that's if you go from HDtv to SD like I do some times, apart from that its all cool.
Enjoy man.