1: A score compared to your previous best on a song... It's all very well getting a score with how much you hit/missed/early/late etc. and a score at the end... but when you haven't got a previous score to compare it to, to see if/how you've improved... it's kinda pointless.
2: More Cymbals. Splashes, Stacks, Trash etc.
3: The ability to delete saved drumkits In-game. It's all very well saving them... but then you adjust and save it again... and then you end up with a dozen different versions of the same saved kit and no way to delete it (On VR at least) without having to plug in your headset and and go through the files.
4: Create a playlist. This would be great, that way you could just play back to back tracks without having to pause, search through your tracks etc...
5: More environments.
6: A better way to adjust the UI. At the moment moving or adjusting the "highway" is an absolute NIGHTMARE! It seems to only half work and if I move it by accident there's no way to reset it on my headset without having to plug it into my computer and mess about with the saved files. Also maybe a way to save the position of the floating menu... since I have to keep moving it and replacing it every time I load up the game... it's tedious.
7: An option to "Lock" drum positions, so you don't accidentally move them... I can't count how many times i've tried to move my "floating menu" and ended up throwing one of my drums miles out of reach.
8: Some different drum "themes" or skins
9: Better hit detection on the Cowbell... that thing is temperamental as all get-out. Half the time it doesn't register a hit.