I have been using a T65 for GPRS and dialup connections for about a year and have been very happy with its performance.
I live a mobile lifestyle (mobile home) and use the phone extensively to connect to various private networks (using its built in modem) as part of my employment. Its not too bad at it either I get 9k6 or 14k4 connecting this way which are very usable for the things I have to do. Even run a Citrix client over it (14k4 is best for that) - its slow but when there are no other options it gets the job done.
However its does have one problem that restricts my use of it, is the builtin modem does not respect the comma "," seperator in the dial string, making it imposible to dial a public number then to connect to a extension inside that number.
I'm keen to buy a new handset that respects the comma sperator and am interested in any advice other may have to offer in the choice of one. Besides a new Vodafone, I am also looking at moving to Telecoms CDMA network, but it seems little is to be gained either costwise or speed wise by doing that.
Speaking of GPRS usage, I surf with pictures off, its cheaper and faster, can't seem to find the submit button...