I'm using it on the Captivate. Friggin' fast, takes a while to get used to - like 15 minutes - then it's rapid. It's also pretty darn accurate as far as word choice goes... all but curse words or foreign words (I'll probably need to include German too if I can).

If I'm in a rush, I'll switch from the Samsung keyboard to the Swype keyboard and I'm pretty rapid with it.