Catan is a decent game, it gets much better with Cities and Knights.
The 6th edition changed a lot of pieces, mostly art style.
This sadly makes it incompatible to be mixed with other editions, which is a rather large negative for anyone looking to replace worn out or missing pieces as you have to replace everything.
So while Catan is fine and BGB is a good seller, the pain in the butt of an art change that no one asked for (and pieces changes in the expansions like the worse knights) make this edition get a lower mark.
Build your zoo, participate in conservation projects, and save the species! The artwork is beautiful, the quality of the pieces is excellent. I would like a few more animals and a few less buildings, but that's a minor issue. The only downside is that the final scoring is a lot of math to fit onto the small scoring sheet they give you. I recommend making your own score sheet, or find one on boardgamegeek.