I liked it, but it hated me and had horrible bugs.
I tried Instiki because I wanted to learn to program in Ruby and so I thought I could contribute. However, my creativity was badly maimed by the beta-ness of the project as well as a horrific "rollback" data loss issue. These were issues so horrific that the project should have been halted. Sure, the developer had things to do, but in my mind there was no excuse. I was frustrated enough to delete my entire installation, including some of my original work. Among the things deleted was an article I wrote with a simple resolution to the "Slashdot effect". Sigh.