We just started using Asana. I've previously used Ace Project, but I found it so clunky. However, now that I'm using something that's much more free form, I sort of miss some of the structure of a more rigid system. My role is primarily managing others, so I do miss being able to see a clear birds-eye of the status of everything. And when email notifications come, it can be difficult to figure out which project a task is associated with. But my team loves it, and I have to admit it's easy to jot down tasks that might otherwise be forgotten. And it's free for smaller teams.