He has been silenced. New mixtape only has a tens of thousands of plays and will never get radio play.

His new mixtape WATER has some great open minded songs. You can DL it for free. https://www.youtube.com/watch?v=ZY6QLFvImc8
https://www.youtube.com/watch?v=CUcjJl7kdpU

He's definitely mainstream. Check out his Wikipage:

https://en.wikipedia.org/wiki/B.o.B

He's a decent popular rapper/hip-hop artist, and has been posting conspiracy stuff on Twitter for some time now.