Overall, I think SSX Blur is solid.
Now that you mention the lack of speech from the characters, it is a little disapointing that there isn't any muttering or screaming from them. I believe there is a bit of incentive to play one character over another; this is from their variation in stats. Actually, I think psymon and zoe have the best overall stats (9+ in each attribute) and I played them the most.
As with the different types of gameplay, I don't really like slalom, it's just not for me. I like all the trick events (half-pipe and slopestyle/big air) and race can be pretty fun.
I actually quite like the music, even got most of the songs from the soundtrack in my playlist now.
I agree with the replays, disappointing that they aren't in this game.
Overall, I'm pretty happy with this game.