Also, there's no open bug tracker. The developer relations people are very friendly, but when I ask where to report bugs I'm told "just tell me". So every 2 months I've reported the same 3 bugs in person and they get swallowed up and that's the last I hear about it until my next report.
The silly thing is that we were one of the showcased applications in Google I/O this year, for the Drive section. A number of Googlers came past and said "Wow, cool. Please, please commercialise this". The truth is, we can't and it's because of the bugs in Google's code (well, partly, the other problem is Drive has just been too unstable over the past 4 months, until there's 99.9% uptime for a year, we can't consider it).
Don't get me wrong, I love what Google are doing with their API stuff and the dev relations really go out of their way to help (specifically the Drive SDK team). But, as it stands, this isn't a platform I'm confident in building a critical business product on, currently.
EDIT : That last sentence is wrong. I'm confident to build a critical business product on it, I think it'll get there, I'm just not confident to charge money and have to support it, at this point in time.