not so good.
Ths is why i beleive this game isn't great.
First of all it is an obvious "copy" of games like guitar hero and rock band or even frets of fire. Note: i do not consider rock band a copy of GH because they actualy made it a full band, but its still darn close ill admit. just because of this you loose on originality side.
Graphics: well for this kind of a game in a flash, i understand intensive flash graphics would be a killer so its not to bad, but still a back ground image or something would have been nice.
Sound: Sound is what it should be, pretty darn good, nothing much to say here.
Gameplay: I am disapointed. You chose a kind of game that already existed. You made a rock band/GH/FoF "copy" took away the pick (wich is almost half the game) and gave it a DDR look/attitude...but DDR is ment to be played on those DDR carpets, not on a keyboard, and RB/FOF/GH can be played with a keyboard, if done right you keep the frets and the pick and even a similar position. You lack these key elements that could have made this game shine a bit. ALSO, despite the "low" graphics, your game is hella lagish, wich sucks in a game where timing is CRUCIAL. and no it isn't my pc, id be surprised if a normal flash can make a pc that runs deadspace at full graphics without lag, lag. big nono here.
Story: not much to say, you didnt have one...and didnt need one so its fine here.
Final note: You had a wonderfull idea and the game ad wonderfull potential, but even considering the fact its a flash, you aimed way to lower to the games of the genre that exist. Not only that, you mix mashed it a bit, screwed it up a it, took away any nice visual candy and slapped in some lag. This game doesn't deserve front page.
This was my opinion of this game, sorry if it was harsh or sounded harsh, i was just quite disapointed, THAT BEING SAID, if ever you plan on making a second rhythmworld, ill be happy and glad to try it, i just hope that if you do i can taste a game that lives up to your abilities and its genre (considering its a flash game of course)