Dislike the most: Loading the layers onto the frame. I have a bad knee and can't stand for more than a few minutes at a time. I don't mind the actual quilting part since it's easy to take frequent breaks, but loading it is a royal pain in the patootie.
Dislike the next-most: This one is kind of funny, but I'd rather make a sampler quilt instead of a quilt with the same block repeated over and over and over. I get soooo bored, and have waaaay too many same-block UFOs.
Minor annoyances: Being on a roll, then having to stop and wind the bobbin. And un-sewing, of course. Ugh!