I don't think I've ever owned a car where I liked the seats at first. It is always a little different and takes a little getting used to. The problem is some cars have bad enough seats that you can't get used to them, and having M3 for a short time I can't be sure, but almost everybody says they are fine so I didn't worry too much when I bought it, although I did find them a bit too narrow at first. I think I've read somewhere that LR vs RWD seats are different, but I can't find it anymore, so maybe I imagined it.
P.S. You wrote comfortable instead uncomfortable in the message, you may want to fix it.