Got my tablet today after a miracle in the post office and started playing. The transition from a mouse to a tablet feels kinda big at first glance, but now it's starting to feel like playing with the tablet is just right, like if osu! was supposed to be played with a tablet from the very beginning.
The tablet is awesome. Its size is just perfect for the game, but I reduced the active area a bit so I could place my hand better. The pen doesn't feel heavy at all, but quite unbalanced because of the battery. Its not a nuisance to me by the way, just a comment. but I had to disable one of the buttons because I kept hitting hit during gameplay lol. So far I think it was a great choice to start learning tablet play, but I feel I'll need a week or two before I get completely used to it.
Just forgot, I had problems with the bundled DVD, I couldn't get it to work (maybe it got scratched during the way here), so I downloaded the drivers from the Huion page (420), restarted, plugged the tablet and it worked just fine on W7.