I've definitely had mixed experiences with AirBnB. When it's genuinely someone renting a spare room on the side, it tends to be a neat experience; I had several of those traveling in Australia solo and it was a good way to get to know the area. I also had positive experiences in Rome and LA with similar arrangements.
When it's just landlords short-term renting a furnished apartment on the side, the experience tends to be subpar. The worst experience I had was in Chicago, when it was clearly a condo owner breaking the terms of the HOA for their building--they told us to say that we were 'just visiting' the occupants of the apartment, not to unlock the door if an actual resident was nearby, etc. The general feeling of "sneaking around" was unpleasant.
It's a mixed bag--the original idea of home sharing is a great experience, but clearly not the most profitable aspect of their business. I wonder if they could figure out ways to support that better...