3 is so bad round here, that I cant even load their site to do topups without images timeout out and waiting 5 minutes.
I used them on a 3g dongle for a while but it was a pretty aweful service, now for 3g I just tether of my O2 phone which is way faster than 3.
Of course O2 dont allow tethering officially but its only occasional use if I have no access to a fixed line broadband service so I get away with it.
O2s charging is a bit confusing also, they list a high charge per mb, but also say the daily fee is capped to £1.01.
I tested it one night be tethering and watching some streams, if the charge wasnt capped I was heading for a bill of at least £50 and got billed £1.01 so O2 seems to be (On web daily) unlimited use for £1 per day. With all the FUP rubbish forbidding high use, tethering etc.
I think mobile broadband is far from ready for heavy use yet.
BT Infinity 2 Since Dec 2012