Blur deserves much more than this
Blur is one of the most enjoyable games I've played for a long time. I disagree when you say it is a poor imitation of Mario Kart. Yes it borrows heavily with regards to the weapons, but I think it's a major improvement, Mario Kart has had it's day, Blur is a fresh look at the genre.
You say the drift mechanics let the game down.. I'm not a fan of drift racing but nailing a hairpin sideways and using the nitro on the exit is one of the most satisfying 'moves' I've experienced in a racer. Maybe some more practice will change your mind here? ;)
You moan about 'numerous route-dividing chicanes' that are missed because you're concentrating on weapon collection and the attack from other racers - surely this adds an extra layer of skill to master? As for the comment "time and time again you'll ram into course dividers", may I refer you to my previous comment about practice? Of the numerous hours I've spent on this game so far this has happened a hand full of times and just reminds me to concentrate more in future.
Online play is 'practically unplayable'? I disagree. I have had a lot of fun online, finishing in all positions from first to last, even when I have come last this only makes me want to play again and try new tactics.
I'll be honest, I've only played the Split/Second demo, which was very disappointing; one track, one car, nothing else. I thought the car felt heavy and the sense of speed was very lacking for a game with a title like that. I will play the full game at some point and my opinion may well change, but for now I'm a Blur fan and I feel your review was very harsh.
I'll shut up now.