They cite 2Mb minimum, but aparently that's not enough. 5+ is recommended.
Keep in mind that:
- Resolution stuck at 720p. Most people have higher resolution displays, so it ends up being scaled, windowed or banded, none of which is ideal. Not to mention a lot of us use 16:10 monitors for gaming rather than 16:9, so in that case there's always banding.
- It goes over the internet, so there is lag.
- Further quality degradation and lag due to compression. You can't send a full-quality 720p signal over the web, the bandwith requirement would be ridiculous. (around 70 M
Byte p/s iirc)
(aparently the quality shifts dynamically according to how much bandwith you're getting at that moment. The more it can use, the higher the quality)
It does have it's uses: you can play on just about any junker (including laptops

), and you can try out games that don't have a demo... which is pretty much all of them nowadays. It does allow console-like PC-gaming on your TV, but with the mentioned drawbacks.
Personally I'll never use it beyond demo-ing, if at all. I much prefer gaming without lag, without a required fast&stable connection, without blurry or banded graphics and without sound-quality loss. Oh, and without a subscription.
To be perfectly honest, I hope it dies, but that doesn't seem to be in the cards anymore. Wide-spread adoption would effectively turn PC-gaming into console-gaming and would likely put an end to technological advancement.