I think it depends on what you're looking for. If you're heavily into the
40k universe I'd say go for it, but if you're just looking for a fun, lightweight space/naval game then I'd try Full Thrust intead if I were you.
The rules are similar in many ways. Basically BFG feels like a slightly simplified version of Full Thrust (not that FT is especially complex). Actually my first thougth when reading Full Thrust wa to start playing BFG with the FT ruleset, since it has a lot more options to offer.
I love the 40k universe and I've played BFG a lot and always had fun doing so, but I'd be lying if I didn't say that I think Full Thrust is the better game
From a financial perspective there's simply no contest. You can get a decent sized Full Thrust starter fleet (like
) for the same price as a single BFG battleship.