I don't hate it in itself, and I think some AGA games look amazing (Ruff 'n' Tumble springs to mind as an example).
I think what a lot of people resent is that it was too little too late, and that AGA was so quickly overtaken by other platforms' graphics hardware with no hope of an update from Commodore 
Too little, too late. After about a week owning an A1200 (from an A500), it became obvious the biggest step up was 512k -> 2MB chip... There was a few nice bits and bobs... But it did suck.