I had a look at one recently and when online the response time just getting to the basic high volume sites like Google News, MSN, etc. was just painful and made me think that I was working with Dial-up.
The real core of the issue is that Apple is using Cingular (AT&T) and their EDGE protocol. Which from what I hear is stuck in < 100 Kbps mode.
Now, I have Verizon's broadband and when tethered through my USB cable I did a speed test (www.SpeedTest.net) and got 1.2 Mbps dowstream and 0.7 upstream - that just blows EDGE away. Going over bluetooth it was about 300 Kbps - still superior to EDGE.
So, I'm glad there's all this hype for now. The guy who showed me the device was all excited about it, but I was under-whelmed at best - heck, a big part of the device is about connectivity and I can't fathom a crappy connection. But, as the penguins did in Madagascar, I just smiled and waved....