I'm on it right now at a restaurant. Works pretty good. I'd say faster than my iPhone 3G.
Edit: it was easy to setup too... Just enter your name, setup a login, and credit card. Processed it right then and sent me a popup window 1 minute later telling me it was activated.
I turned on the wifi while I was at home. I got a AT&T 3G connection even before I signed up. So not sure if it would work without WiFi or connected to iTunes.