I disliked the logo being in your face all the time. I remember buying it. I don't need to be reminded where I bought it from all the time
. Fine on the back!
Not fan of the chin either. I think the Studio Display gets the Apple design aesthetic right, which is cool minimalism at this point. I'd like to see an iMac based around this design but I'm not sure it'd work that well without the chin due to the display height versus size.
Actually the worst one I had was the first Intel plastic iMac. That was 80% frame with a small screen wedged in it and a massive apple logo at the bottom. Really disliked that one.