I bought the game... after playing the demo one of the songs got stuck in my head and the next day at work I caught myself zoning out thinking about digital fireworks... so I bought it when I got home.
I knocked out 3/4 of the achievements the first day through. they're not very balanced IMO... at least not points wise I only have 3 achievements left and I don't even have half the points yet.
... I'll get the full 200 though

I'm pretty close to getting the last 3 done... I've managed 4 1/2 laps on endurance hard I've only got 3 more songs to A-rank in Medium and 3 more fireworks to collect on hard... I probably would have finished it last night if I didn't take a break to play Gears for a few hours.
Some advice:your letter grade its based entirely on accuracy but you can't go just by the accuracy rating since it doesn't consider missed rockets. Multiply your % accuracy by your % complete a result of 86.5% or higher will generally get you an A it fluctuates by about half a percent on a song by song basis.
With that under consideration avoid using bonus mode, it's completely useless for all but 1 of the achievements (the activate bonus mode achievement) all it does is boost your score for a higher leaderboard position.... and your score doesn't factor into your letter grade one iota.
For getting better accuracy ignore the line at the top of the screen and push the buttons based on the beat of the music... the line should only serve as a rough guide as to what is coming up next.
Also I highly recommend ditching the arrow marked rockets for ABXY marked rockets, as a DDR playing the arrows just screwed me up because I kept trying to play it like DDR... I know the ABXY positions and colors well enough that it associates just as easy as arrows. (even easier when you consider a left arrow appearing on the right of the screen after a right arrow appearing the left of the screen can really screw you up by creating logical conflicts).