I've been giving serious thought to prototyping in BB specifically for 2D. My main concern is that with BB3 being primarily focused on at the for the last while, that the 2D development might stagnate. My main focus would be on platform/platform shooters. The idea of the logic pieces is great, but sadly there are some important ones missing for the platforming genre. Hopefully more are planned and this was my main concern - that the 2D dev would die off. I am a professional 3D artist who is very comfortable in my main engine(UE4), but love the idea of just being able to jump into BB very quickly and effortlessly throw prototypes together, without any of the setup/heavy lifting that UE4 requires. Also, I see that BB3 will feature a nodal logic system(like UE4 Blueprints) and was wondering if this will be available in the 2D engine? I don't really have any interest in the 3D aspect of BB3 because.......UE4.... Cheers.
My advice is to keep an eye on BB3 for when it does incorporate 2d into bb3 and until then keep learning the software you are most comfortable with or another that has dedicated 2d already. Main reason I say this is because BB3 is still in beta and I don't think their next release is focused on 2d so it probably won't come until next year some time.