Yes, I've not had any major issues with a SanDisk 32gb card, a couple of issues with it not mouting correctly when trying to connect it to my computer and use it as removable storage but I get this occationally with the supplied 8gb card too.
Tested with my friends to start off with, and I've since been out and bought my own, you can buy and use with confidence, using mine mostly to store movies (only so I can showcase the phone - I find myself daily needing to justify why I didnt buy a Desire...).
Currently only about a hundred meg free.
It will become a lot more useful once the phone is rooted.
£100 for a SD card is a lot of money... If I were to do it again I probably wouldnt have bought it when I did, knowing my luck by the time we've rooted it they'll prolly be a third of the price!