Only qualms I have with the BC29 are:
1) The fans. They almost always end up making a horrendous screeching noise when you first turn them on. Replacing them with an aftermarket fan is cheap, gives you better cooling, and avoids the issue altogether. This is even more important when you're buying a used BC29.
2) The return pump isn't powerful enough, imo. You can replace it with a Maxi-Jet 1200 to get a little better performance out of it.
3) The stock protein skimmer they sell for it is poo-poo. It works, but the cup is so tiny that it fills up in no time and ends up spilling over back into the tank. Get yourself a Tunze 9002 with the upgraded skimmer cup if you want to use a skimmer on it.
Other than that, it's a solid tank. Don't go drilling it or anything, though; they're well known to crack after having been drilled, due to the glass in back being so thin. Not worth the hassle, imo.