Pity CREATESCREEN/USESCREEN won't work. There is so much you can do with that. As for orientation issues I haven't experienced any even with GLB version 10 but then I've been sticking to a fixed orientation and editing the manifest.xml file.
Mostly my experience has been that the Nexus 7 runs things so fast & smooth that I get overly ambitious with my code. For example, I wrote a particle engine on the weekend that works wonderfully on the Nexus 7 but the effects it creates can get very slow on an old Nook Color when I've got many hundreds of particles moving, rotating, changing colour, etc. Worth keeping a slower device around just to get a sense of what some users are going to have to put up with.
Some games that have been published in GLBasic don't seem to work. For example, I couldn't get Q*Boyd to start.