I haven't been to Busters in years and thought it was decent before I moved to Texas, now it's just kind of average in my mind, HOWEVER, this is more about Famous Dave's and how trash that place is. I'm sorry but it's not BBQ, at best it's stuff that's baked in the oven and tastes like they toss a little liquid smoke on it and then slather it in their bbq sauce. This might be harsh but I wouldn't step foot in Famous Dave's.
As for other BBQ places in Portland, Reverands was pretty good, didn't get the hype over Podnah's, and Goldie's over in Vancouver was my favorite (though personal bias since owners are long time family friends) but they closed down after issues with the neighbors and landlord.