So, Wizards released the GSL.
I’m not sure I see why anyone would use it.
I haven’t read through it in detail, but it doesn’t seem to actually grant any worthwhile rights. The OGL was arguably worthwhile. You agreed to abide by WotC’s restrictions. In return, you got to use a whole lot of content more-or-less as you wish.
The GSL? You agree to abide by WotC’s restrictions (which are more restrictive than before). In return, you get to refer to WotC’s content (but you can’t quote it or alter it).
I’m not sure that the GSL actually gives you any rights that you don’t already have.