There are lots of little bugs that I hit, which I'd be happy to report on.
One thing I'd like is some way to click on a node and have playback restart from there. If I make a rhythm that has a really nice groove, I might be inclined to feel the "1" at a certain spot. And while it's possible to switch to feeling the "1" somewhere else, that's often tricky to do. Being able to click nodes (or something) would help me reset my internal sense of the rhythm and feel it different ways.
I could also make an argument for adding silent nodes. (If the volume had upper/lower limits instead of wrapping around, I could just make a node and turn it to 0 volume).