Yeah, as spangenberg says, it's alright with Launcher Pro running, the stock UI is just bad, and constantly freezes up the device. With Launcher Pro though, it performs similar to my Moto Droid. No Market by default. Trying to get USB Debugging enabled, but a lot of the menu's are hidden. You can sideload apps as long as you can find an APK.
Basically HP wants you to just use this thing for printing. You can add HP Print Apps from HP's market, pretty much all free as far as I have seen so far, but you really can't do much with them except print whatever it is.
I like the Print Apps and they seem like they could be useful, for certain things though, so I'd like to keep that access built in, but I think they could of definitely done a better job with some of them.
It's absolutely 1st Gen, and pretty much should be considered a beta product. However, it's got some decent hardware, so with the Market and removal of the HP UI, it's got some real potential to be a decent tablet/printer/scanner until a real Tablet with Tegra 2 and Honeycomb is available.
EDIT: That is... as long as your in the market for the printer/scanner too.