I actually own a Pandora.
Besides the one usb port on it being a little strange, it's worked wonderfully for me. I had preordered it, but ended up just paying the extra money to get it shipped sooner. I have yet to regret it. I would advise getting at least one fast 16GB SD card for it, so you can have plenty of programs, but the Pandora is able to emulate psx games. I've also watched videos on it without any problems. (PanPlayer works the best).
The keyboard is a little strange, but the screen and battery life is amazing. Wifi works pretty well, especially if you run 'sudo iwconfig wlan0 power off' to turn off power management of the wifi. (The power management thing is a problem I've had with many wireless cards under linux. In this case the wireless works fine without the command, but if you're transferring a bunch of data over wireless, you'll want to turn off the wireless power management.)
And yes, it does fit in your pocket. It's a bit bigger than an original GBA.
If you're willing to pay around $500 for a pocket computer that gets 10-15 hours of battery life, I would say the Pandora is worth it.
I personally do wish that the Pandora team was more transparent, but from what I understand, they've been spending all their time working, and building pandoras, instead of soothing the community. I hope they can get enough support to keep the project going, but I imagine it's pretty difficult to make something like the open pandora when you don't have a boatload of starting capital.