I've found that if you are looking for just a private room, you can get a deal. But then you are also in a stranger's house, which as a 30-something I'm not always that comfortable with. When I travel with my wife, it's not even an option.
When I look at entire home/apt listings, the prices are often very comparable to nearby hotels, and often I can get a cheaper hotel using an "opaque" service like Hotwire or Priceline. As between the two, I'd much rather stay in a hotel, since they are set up for travelers and I can get whatever extra towels, amenities, etc. that might be missing from an AirBnb.
AirBnBs are absolutely more unique than hotel rooms, but that isn't always a good thing. I've had too many late nights sat outside a property waiting for the owner to turn up, too many broken fixtures (including heating) with no-one to repair.
And (as the other poster mentioned) I've been very surprised to find out that these days AirBnB rates for "whole property" aren't even competitive with hotel rooms, especially when you factor in the "cleaning fee" and other such spurious fees that seem designed to make it difficult for you to calculate a total easily.