I dislike both the interface and the community.

• I have enough experience building large high-quality software projects (my business) to say the interface is crap and know the reasons for it, not the least of which is the hubris of the principal developer and the technology it's built on. The sky's the limit on Go interfaces. Quite frankly, they're all "bad" in that none of them have impressed me. I would guess the reason is that none of them have really been financially successful other than the oldest ones, so there is little incentive for someone like myself who has too many other things to do than build a fancy Go server. The rest have been half-hearted side projects. OGS + Nova merger has been a recent success story, but I also think that one is not managed as well as it could have been. (Maybe I'm growing too cynical...)
• Even at the dan level, KGS is full of players who would rather game the system than play go and win (or lose) according to the game, not spam moves to run opponents out of time, click the undo button a bunch, leave just often enough to avoid losses, etc.

There are five hundred different ways these projects could be more successful from the get-go, but there isn't time nor money to really build it ground-up the right way...