Lr3b is usable, and many people will begin using it instead of Lr2.6 (heeding safety warnings of course...). Unfortunately, many plugins are not compatible, yet.
At a minimum, please fix the bugs that keep unchanged functions from working, e.g. exportSession:photosToExport().
And hopefully, toss in a few functions for accessing develop settings, collections, filters, sorting, and the full complement of metadata, ...
I agree. I've been working on Web module gallery engines and can provide feedback on a beta SDK if it were available.
exportSession:photosToExport() is working in Lr3b2 (it was broken in Lr3b(1))