If you don't like this movie, read this post...
Ok, I'm stunned to see so many people acting shocked over this movie, apparently completely unaware of two important factors, namely that this was an intentional comedy, and secondly, that this is the THIRD film in this satirical series of Brady send-ups.
The first two movies were The Brady Bunch Movie (1995) and A Very Brady Sequel (1996), and both of them were absolutely hilarious, especially for fans of the original show. Many of the original castmembers did cameos.
Anyway, it's a real shame so many people didn't understand what this was, and cried foul (assumedly because they thought this was somehow harming their beloved series, which it really wasn't, of course), because it now appears such negative reviews have completely killed their future plans for additional sequels (God, I was so looking forward to the next one, wherein the family gets shipwrecked on Gilligan's Island!).
So take a breather, folks. This wasn't some insult to the franchise, it was intentionally meant to be a funny parody, fully "approved" by the official Brady powers-that-be.