A lot of it depends on how closely they follow the android environment, the keyboard/mouse availability (1 usb port? Why?) and if it gets some decent programming tools with it from the get-go.
I'm looking into developing for the android OS myself, but not necessarily for this platform. I can see it as an awesome thing for kids to get into the world of coding and games creation though. A C64 for today's world, or kiddy Linux for the masses. Whatever way you want to look at it, I think it is a pretty cool idea. If you're buying this to play AAA titles, you'll probably be dissapointed. But for a hobby coder it should be great, plus it will give you "reasonable" skills for the future if they can make it relatively easy to port to mobile/tablet environments.
If they had something like this when I was a kid, I'd be begging my parents for one. So much better than GWBASIC, QBASIC or TP6 on an old 286. Plus you can show your stuff off to your friends so much more easily than on a PC. Just take your console to your mate's house, plug it into their TV, and start playing (on controllers that all your friends will understand). I think it's a cool idea, for hobby coders, kids getting into coding, and even people like me who'll just be using it for old school games on a telly.
I'm getting one for the emulation possibilities. But I know I'm going to muck around in the SDK at least a bit. Boy I hope the slap another usb port on it before main release. Or I'll buy a hub I guess.
Also, who said this was open source only? It's a try-before-you-buy, a freemium, and even freeware platform. I haven't seen anything about stuff "needing" to be open source. It can be if you want to develop under the open source model, but it doesn't have to be AFAIK.
One hundred bucks to show my mates what a leet-uber-coder I am in between rounds of SF2 and a few beers? Yep, for sure