I came to Airbnb with prior couchsurfing experience. You learn how to distinguish good listings from bad. Every single one of my Airbnb experiences has been both inexpensive and awesome.
Some markets are tougher though. Manhattan is extremely expensive. Most other cities seem fine.
(Granted, it was something like a fifth-floor walk-up, and the neighborhood was a little gritty, but in the edgy-up-and-coming cool-if-you're-into-that sort of way and not the help-get-me-out-of-here fear-for-your-life drug-dealers-on-the-doorstep kind of way.)
I can only expect that I'd be out another few hundred bucks if I used a traditional hotel.
Irrational exuberance of startups around here tends to get out of hand. I get it. Everybody is the friend of a rich person and you want to promote them because you know them. hi-5's and bropong all around. Great. But they're still delusional. Gotta speak truth to ego-elevating unrestricted happiness. Life is pain, not million dollar post-exit condos in SF.
The cleaning fees had some wording like "if necessary" or "if damage is done," but it was never returned or communicated nothing would be returned.
(Sidenote: There's also no recourse or discount for "weirdness." The lady whose second bedroom I rented had her non-english-speaking mother stay for two weeks (unannounced, unasked--suddenly there was just someone new living there) whose hobbies included power sanding furniture starting about two hours before daylight and taking up the entire kitchen for five hours a day.)
The response rate things are okay, but there are still tons of people who cannot communicate effectively online (or even form coherent thoughts in person most days). It's a crapshoot. (Kinda like trying to sell things on craigslist -- you never realize how many weirdos are out there until you have something they want. "Yoooooo maaan... will you take some pot for tha xbox? we aint got no monay.")
Hell, I'm not comfortable reviewing an air mattress I bought on amazon.
Why is it so flatly awesome? My experience was: overpriced room (overpriced because the high airbnb fees get passed on to the person who stays), annoying extra "cleaning/deposit" fees that don't get refunded (and you're not notified that they didn't get refunded), and a quasi-too-personal system of booking where half the listings are by weirdos ("RENT A ROOM IN MAH CAMPER ON THE STREET!") you can't filter out or fake listings nobody responds to.
It's squarely not in my "things that make me happy" column.