I switched to BB a couple of months ago after being with Netflix for over 6 years over the Blu-ray availability issue. I don't know if it's because i was a new sub, but BB was giving me everything at the top of my queue, even it was on Long Wait or Very Long Wait.
I don't think BB has quite the number of releases on BD as Netflix. Case in point, Netflix has had Black Snake Moan on BD since its release, but on BB its in my Save queue awaiting its "release."
The in-store exchange was also pretty handy until my local BB went from a 7-day to 5-day rental policy, meaning more than one trip in the car per week to return movies. (I think they also eliminated the "no late fee" one-week grace period before charging your credit card for the full purchase price of the movie).
I am not unhappy with BB (their processing and mailing times were as good as Netflix), but I will likely switch back to Netflix in the next month or two before the 90-day hold period on my account is up.