I think it'd be a good idea to have the option to select the keys, either that or in my case the up and down keys need switching because I mentally understand the up to be on the left and down to be on the right(doubly true of WASD where the W is actually on the left). On the higher difficulties with no time to see the notes coming and think twice I always instinctively press them the wrong way around, every single time.
Maybe a practice mode too so you can actually learn the songs a little.
UPDATE: The new version is greatly improved.
Congratulations on the successful funding!