I actually quite like the preflight dining at BOS - it's usually a decent selection, and their desserts are very yummy (in my experience usually involving lots of chocolate sauce...). Service can sometimes be a spot slow depending on staff, but overall definitely worth an hour or two of your time.
B/F onboard is ok, but as suggested by nomoreiphone, I'd definitely wait until the arrivals lounge..

Cheers,
pcf