Own... no. Have used in anger, Yes
I don't have one to hand but I will try and answer any specific questions you may have. My quick summary would be... the first out-of-the-box impressions don't 'wow' like a HTC phone does, as the software isn't as flashy and pretty. But it is very solid, feels like a premium device, the software adds real value where it counts (performance and battery life!) and once you settle down into normal use, you have a phone that's very, very hard to better overall.
IMO the initial wow factor is all well and good, but once the frustration of onscreen keyboards, poor battery life and other such impracticalities take over the experience goes downhill. This is much, much less of a problem with the Milestone 2.
As said, fire away questions and if I can't answer I'll either say so, or I'll try and blag another test drive...