Looked into docking my boat there a few years back. As I recall it was just a so-so marina, with facilities that were far from luxurious. Where it did shine however was the fact that it ALLOWED liveaboards in the first place. This alone turns an average marina into a gem!
As far as shelter from bad weather goes, it wasn't too bad, being tucked aways back in from the Gulf. However, the best thing about the St. Pete area is that hurricanes generally pass either north of south. I can't recall the last time St. Pete or Tampa suffered any serious storm damage.
Good luck! BPM may not be the Taj Mahal, but there are a lot worse places to hang your hat.