I agree the piano roll could be improved but would prefer to see note editing remain touch based rather than using kicker tools or grab handles. As mentioned Beatmaker and Nanostudio use them and it seems unintuitive to have notes on screen but touch elsewhere to move them.
A touch screen interface should focus on touching the elements you want to move rather than touching a separate button to move it, this draws your attention away from the job in hand as you are constantly looking for separate buttons away from the item you actually want to move.
Garageband for ipad midi note editor works much better in that if you want to move a note, you tap on it and move it, if you want to resize just hold the note till it changes to "resize mode" and drag, simple. A long tap is the iPad equivalent of a Windows "Right Click" and is the simplest way to alternate edit modes.
Having said that , I know the full cubase has kicker buttons so i wouldn't object to both methods being implimented but please keep / improve the touch note editing as this is the main reason I don't use Beatmaker or GarageBand which are otherwise excellent apps. It drives me crazy when I try to move a note in those apps and it just sits there !
As far as I'm concerned apple have got note manipulation spot on in GarageBand , I hope you can get some ideas from there