I'd say internet over a cell phone is slow, but it's probably faster than dial-up.
I have an unlimited data plan for my cell phone/pda and I love it, but I use that only for when I'm on the road. At home/work I have broadband.
I wonder how unlimited my data plan is though. I guess it's one of those fair use things. So I don't use it for everything, but I do get up to 20MB of traffic on it on a "busy" day (web browsing, e-mail, trafic info).
Don't they warn you first before you get kicked off? Or do you always need that much traffic?