I tried them a year ago. At the time they seemed great, tech support was responsive and they seemed on the ball. Unfortunately they depend on the local bell company to run the DSL line. The phone company delayed and stalled and when they finally did install the line it was crap. I ended up with a whopping 60KB, even though I was listed at 11,000 feet from the CO. At this point Telocity said that there was nothing they could do as the depend on the phone company who could not possibly care any less than they did. I returned the modem a year ago.
All was well until a few weeks ago when lo and behold Telocity sends me a bill for the modem! After a year they send me a freaking bill!!!! What A$$H*les!!!!. Even though the bill was charged to them (part of their guarantee back then) they decided that I hadnt sent it back. Luckily I still have a bill from Airborne express for the shipment which appearantly Telocity didnt pay for. I sent a scanned image of the bill back to telocity and a week or so later they said they will investigate and get back to me. I'm still waiting. I hope this isnt a tactic for them, wait an unreasonably long time and then just bill past customer for not returning the modems, hoping that the customer no longer has his shipping reciept in order to make an easy $500.
So at this point in time i would have to aggressively recomend that you and everybody else stay as far away from them as possible.