The original input control was something that I had going pretty fast, honestly. But making everything feel GOOD was another matter. That, plus dealing with things like hitboxes for a very non-humanoid character, which is pretty uncommon. Using some IK and some ragdoll physics in combination with traditional animations let me work around the clipping issues, but even there I had to do some tricky things with hitboxes that are only sometimes active, etc, to keep things from getting nutty in some jump cases, etc.
It works out well, and for a character controller of this sort it's actually not so complex in the end. But I must have tried like 40 wrong approaches that I wasn't happy with before getting a compound one that I do like.