Well I have had the phone for more than a month now. I am quite impressed, I did get a bill within 3 days for 3.11 but then it was the end of the month. This month should be cheaper, it's only my text package that ran that up.
In terms of technology I am very impressed, the switching is indeed seamless, the only way I know it has switched is by looking at the display. Although the phone can use wlan the basic software does not allow for sending/receiving files over it, but it may be possible to write a java app for it.
The only real thing I have noticed is that the GPRS is really slow (unless I am at home, then it hits 8 meg) but signal strength is really good.
It's also quite useful for checking if there is any wireless networks in the area without unpacking the laptop.
Well worth it I think.