Since the game's release, I've probably spent close to 80 hours on it so far. And you know what? I've only unlocked 19% of content so far! There are a ton of things to do and unlock. There are characters(that players can use as avatars) to unlock, interfaces to unlock and music videos to unlock. The game utilizes a level system wherein as more playtime is recorded, players gain more "experience points," which leads to gaining levels--as players become higher in levels, more contents are unlocked. This system allows players to constantly unlock more contents as the game is played more. More or less, I had something to unlock every time I got to play, and the feel of game exploding in size is pretty satisfying.
The game's music videos are what anyone would expect in this type of games--animations that are probably made using Flash technology, but good enough for these types of games. The animation is stiff, but they do utilize PSP's resolution and so are very clean.
The game in itself, now that I think of it, is generally what most anyone would expect of rhythm games--press buttons in correct rhythm, as guided by falling graphics. There ARE few things that does set DJ Max fever apart from other games and they are:
Customizable button placement - map buttons as players like to play;
Original music - all the music scores are composed more or less exclusively for the game(unless you count previous DJ Max games, which from what I know uses music also used in Fever). This is a change in comparison to other music games like Dance Dance Revolution and Elite Beat Agent in that the songs are fresh.
This game was a surprise for me. I honestly bought it not expecting much, but because the game tried to make itself stand out with its unique features and music, I think the money was worth it.