I'm down in Florida for vacation and just played on clay for the first time (or Har-Tru, as it were).
Anyway, the ball definitely bites and jumps up, but I haven't noticed it to be tremendously "slower". Perhaps I don't play with enough pace.
Also, I got used to the sliding pretty quickly. Except when I get completely engrossed in a point and stop thinking about needing to slide. Then I almost end up on my rear. :-)