I had an unlimited "phone as modem" (PAM) plan from Sprint before getting the Evo.
I'm actually using more data on my Evo than I did on my laptop most months!
I'm paying for the Hotspot feature and I've used less than 1gb on my laptop... whereas I easily went over 5gb this past month. Heck, according to my Netcounter App, I've already sucked down over 3gb on my Evo in the past three days.
That's me surfing the forums, downloading/streaming video and audio podcasts, watching SprintTV, TV.com, and YouTube.