I am way too excited for this version of the application. My favorite addition is the low poly modeling room (Where I have been playing!). I hope transitioning between rooms is streamlined as well (Rather than treating them as separate applications, it would be nice to be able to transfer directly between them. Maybe you could before and I just never figured it out!).
An issue I found almost immediately in the Low Poly room:
Reproduction steps:
1: Create a default cube (Where it all begins)
2: Select 3 of the top faces (It was an accident, but whatever finds the edge cases, right?)
3: Rotate the selected faces (Toward the unselected face. Again... accident. Getting used to the tool, haha)
4: Use the Spine tool and pull the selected faces out a few times into a loop (Kind of like the top of a lock)
5: Try to undo it all.