They've posted an extensive review. While the reviewer was careful to note that it was a prototype, not a production model, he couldn't help but wax poetic about its features.
The Go has a smaller screen, but other than that it has better hardware. It has a second camera on the back (with Flash) in addition to the camera on the front. Unlike its larger cousin, the Go is designed with landscape mode in mind; the home button and camera are centered on the long sides of the screen, not the short sides.
While they liked the Go, they also found fault with a number of details. For example, it's too think, and they feel that HP could have shoehorned in a better camera in that space. I'm not sure that's a valid complaint; this was a prototype. The production model would probably have been thinner.
All in all, this would have been a nice tablet. It's significantly better than the original TouchPad. It's a pity that HP didn't launch with this tablet instead of the 10" model; the Go might have succeeded at the original retail of $500.
BTW, I almost got one of these. I passed, mostly because I was outbid, but also because I didn't try very hard to get it. You see, the TP Go that I was offered wasn't necessarily a legal product. I'm sure you know that most companies remove such marks before they sell off their equipment, right? The back of the Go said that it was still property of HP, and that worried me.
Do you recall last year when Gizmodo bought a stolen iPhone 4? They ended up being raided by the police because well, the iPhone was stolen property. I don't know that the TP Go was illicit, but I could not afford to risk it. Also, HP killed both the Ebay auctions that I know of, and that tells me that they really don't want this device changing hands. I was afraid that HP would have played rough in order to get it back.
I would have been happy to sell it back to HP after my review, but the possibility of their negative reaction was a little too much for me.