As of 2 days ago, I have my main desktop running Debian Lenny (currently the testing release, but soon to be stable – more on Debian in a minute).
Read the experience here
Also, Ive never run Debian as a daily-driver distro. Ive tried if a few times (briefly), but Ive always defaulted back to Ubuntu for that – I always felt it was better suited for the desktop, but Im beginning to change that opinion. Im very happy with the install of Lenny and its running faster than any other distro Ive had on here for an extended period of time. I did do a very customized installation (building up from a base system) and I was very selective about what packages were installed. It seems the Debian release team is shooting for a September release of Lenny, and I plan to stay on Lenny for a while after that, but will probably go to Testing again once its nearing release again.