From an end consumer standpoint:
I look at that mini PC and think "wow it's got so much of what I wanted in the pandora..." Then I see the price and go "except for THAT". I dont mind that it's a windows machine because I know the OS, Win 7 is so much nicer than the crime against humanity that Vista was, and there are lots of free programs that I could just port over from my existing computer, but it's still Windows which means tons of bloat in software and an overhead that levels the playing field on processor speed, virus protection updates every hour and the feeling that someone is counting your money and giggling mirthfully as you suffer. Being that it's Windows it means a lot of Emulators are already well ahead of the curve in terms of optimization. Apparently it already has codec support for Hi-def video (probably requires an extra purchase) as well as full browser functionality. Many of these things we're still kind waiting to see speed up on Pandora (understandably some people might say we have flash already, but it's not as easy as hitting the macromedia website to install and 720p video might be "playable", but also not an instant type thing). The upside is yes we have a community that is eager to help, but with a well established brand (the windows & intel stuff it uses) the other side of the coin is that you dont often need as much help... unless the computer itself breaks and then it's "hello faceless corporation that cares nothing for anything but my cash". I had questions about my Pandora the first day and it wasnt more than an hour or so before Craig, ED and others were responding directly to me.
While it doesnt have the game controller buttons it seems small enough that the keyboard wouldn't be too horrible in a pinch for Mame and 8bit games, but it does miss out on analog nubs and shoulder buttons needed for 16bit and higher. You can use a USB pad but you cant really do that standing up on the train or bus which is what I was easily able to do with the Pandora the other day. I dont really have a need for a webcam on the go, that's what my phone or my actual camera is for. GPS, etc. is fun, but c'mon who doesnt already have a phone with all that? Okay, if you don't, this isnt your situation but for some it probably already is, and their phones may already have tethering, forgoing the need for 3G (if you're willing to drop 600 bucks on a computer you probably already have a 400 dollar phone). The Pandora easily stayed on all day playing music and games and even a little wireless internet surfing once I got home, 6 hours is nice for a windows computer but 12+ is better. The Pandora seems to be a little bulkier but it's still easy to port around. Personally, I find that some consumer products look nice and slim on the websites, in reality there's an awkward battery attached that they never really show you (HP's 6 hour battery for netbooks for instance, seriously WTF!? I cant even fit that in it's case with that freakin' kickstand hanging off it). Pandora's flaws are ones that can be overcome with time, while the Mini PCs are ones that could be argued are by design in some cases. They might be ones some people have the patience to deal with, where they might not be willing to spend time getting to know it or waiting for functionality updates on Pandora.
I see good and bad points for both devices. In the end, even with the waiting game for the Pandora to mature, I'm still glad I already have one... and so is my wallet. I paid 330 for it versus the 650 they want for the mini pc, that's 320 bucks I can put towards something else.