Well others have outlined the gameplay elements so I won't repeat that.
What you have to realise when buying this game is that you are not paying for a 10-12 hour campaign. You are paying for a game that can be played through on easy level in a couple of hours. However, step the difficulty level up and the challenge begins to try and perfect your runs, timing your shots well so you keep your combo going to rack up high scores.
A previous reviewer said there are no tactics but I disagree, the choice between spraying your enemies with machine gun fire just to keep your combo going, or risking going more precise for a much more score worthy single headshot, at the risk of losing your combo is a constant one. Similarly, weapon choice is a constant decision.
The fact that there is no story as such and this is primarily a trip back to the good old days of gaming where the sole purpose was to beat your high score will grate some people. I find it a hugely refreshing change.
Multiplayer is good fun and lag free (though last night there were only 12 people in the world playing The Club online)
My only gripes are that the difficulty curve is quite steep. you will blast through every level on casual mode, yet put it up one level to reckless and it gets pretty tough, pretty quickly. Either Casual is slightly too easy, or reckless is slightly too hard. There are 2 further levels which seem nigh on impossible to me so why reckless has to be as difficult as it is I'm not sure. On the flipside, when you nail it and completely blow your previous high score away, it is a very, very satisfying feeling. Also I would have liked to have seen a bit more in the way of unlockable, but that's pretty minor really.
EDIT : Now I've been playing this for a week, I'm starting to really learn some of the levels and although I still havent won a tournamant on Reckless, I'm consistantly getting 2nd place over the 6 events, so it does get possible to take on the higher skill levels, (managed 4th in an Insane tounament too!) even for a shooter neanderthal like me.
PGR4 + Tony Hawks + Tekken + guns = The Club
The most enjoyable shooter for a long time.