The demo itself is roughly around 2-3 hours worth of reading, which is approximately 1/6 - 1/7 of Umineko Episode 1.
Anyway, I personally greatly enjoyed RGD for something fresh to the point you can already have an idea how much fun Ryukishi had while writing it (it did flow quite naturally despite being miles away from what he usually writes).
The other solid point imho was the very minimal "nippon banzai!" (the likes of code geass) which was the very first point that worried me after glancing at the premise months ago: considering the 2012 portions and all, the possibility of having a story revolving around "liberating Japan" is completely null, so it is indeed more focalised on the action than really drama over politics etc.
I don't expect thorough discussions considering the nature of the story, but that's basically the same for other VN in general, so having a "standard" entertainment here before Ryukishi starts another "naku koro ni" series is definitely welcome.
By the way, 07th Expansion has announced RGD goods that will be released this summer:
http://www.07th-expansion.net/2012summer.htm
As expected, the CD albums will be available only at Doujin shops such like tora no ana, so importing them will be a chore...