Locked content is annoying, and timing/input off
Just a couple notes. It's usually annoying to play a game on Newgrounds that says "go to X other site to play half of the actual content!" Most of the time, if I've already loaded the game and put in my name and picked settings, I won't really feel like going to a new site and doing all that over again.
I've been playing music games for years - all the classic ones (DDR/IIDX/GF/DM/PopN/ITG), the new ones (GH/RB). I feel I can safely observe that the input is noticeably "off" and I will get random combo breaks when I'm holding down and hitting notes. It's annoying really. I'll be holding down the notes, strum perfectly on beat and when the notes hit the bar, and get a miss on one of them. And I'll look down at the keyboard and see my fingers on the two notes I missed and no fingers on others. No reason for this, and I haven't bothered sorting out if the timing windows are too tight (which shouldn't be the case), or if there is just some input issue. Alternatively it could be my keyboard, but given that I don't have issues with other NG games I find this unlikely.
On an upside the music is cool and the theme is nice.