I've got bd and i would say that in some areas it is better than fc3 and in some worse. Fighting a dragon is fun but the game feels a bit lazy; I don't mean to be pedantic, but the interior of cars is almost the exact same as in 3 (you can see all the maps that are stuck to the visor) and the jet skis are the same as in 3.
Overall I would say 7-8/10, whereas fc3 is 9/10 (IMO)
"I fear being nothing, I fear having no thought, no feeling, no joy or sadness, I fear nothingness. And spiders." - Me.