I think it's interesting that the mobileread community seems to be pretty much Scribd only. I wonder why that is? Maybe, like Blossom says, because Scribd's subscription service was launched off of an already existing service, you mobilereaders would have already been attuned to Scribd versus Oyster, a new start up. (Although interestingly, Oyster launched their subscription service just ahead of Scribd.) But, Atunah, you bring up a good point about the accessibility on different devices.
I'm also with Blossom on the advantages of the sub services over Overdrive
And Meera, thanks for giving my survey a read, but as question 15 is about ebook subscription services, I did not put eReader as an option since you can't use ebook subscription services on an eReader (eInk).