Yeah, I loved AFFC. It's not my personal favourite, but I think it's easily on par with the first three.
I'm technically not a long time fan, though. Got into the series four years ago, but that was still way after AFFC was published. I've read on various sites and whatnot that some fans were disappointed that after waiting all those years, Feast didn't include all of the characters they had grown to love (or hate) in the first three books. But for me, I knew going in who and what wasn't covered in the book and how it was only one half of GRRM's original vision for Feast. That might have made it more enjoyable for me since I didn't have any expectations that it failed to meet.