Blur IS a kart racer. You race through events with between 9 and 19 other racers, pick up powerups on the track that do various things (long range homing attack, series of three straight-line "bolts" to spin out your opponent, etc.), of course with some "modern twists" thrown on, namely that as you race, you go up in rank, which unlocks new cars and what they call mods, which modify either the performance of your car or your powerups, for instance making it so any time you drop a powerup on the track (as opposed to using it, just ditching it), it drops a decoy powerup, or just making it so that your car takes less damage from other people's powerups.
It's a ridiculously fun game. I spent about 24 hours just playing the demo on Xbox Live before the game came out. One of the interesting things about it is that it has a pretty solid learning curve. If you just jump into ten-player matches, you can usually do pretty well, but 20-player matches are crazy and winning (if you're insanely lucky, if you're just lucky, you might get top 3) takes some serious maneuvering, knowledge of the track, and strategic powerup use.
I know they put the demo back up on Xbox Live after release in an attempt to drive sales. Not sure about PSN or if it's still up on either, but honestly I would recommend that anybody who enjoys kart-racing style games with powerups check it out in some capacity.
And yeah, I know that they didn't SAY anything about Blood Stone, but you really think that this coming out two weeks after the game tanked both in terms of review scores AND sales is a coincidence?