I've got Infinity and have to say it's great. On ADSL the best speed I could get was around 1.5Mbit as we're a long way from the exchange. The Infinity website said I'd get 24 download / 8 Upload and I'm usually getting 30+ download and 9 upload so better than they predicted.
It's a long contract but I also know Virgin won't cable my area until 2012 so it was a no brainer for me.
How far from exchange are you? also was it fast switching over? i been deciding over this all day lol.