I try to at least leave a few words of praise even if I don't say anything specific, but sometimes a fic will move me to really go in-depth into what I loved and what worked so well. I do always kudos, though!

Oddly, it's easier for me to review art. Maybe because there's not as much to talk about? I can mention one thing that I really like about the piece (expressions, colors, poses, etc.) without having to worry to much about "missing" something.