My family and I just stayed in a bunch of airbnb's in Europe, with mixed success. I did gain a lot of additional insight into the pros and cons from the experience.
First, reviews are definitely not very reliable. You MUST avoid unreviewed properties and anything less than 4 1/2 stars, but even the better properties are risky. People are just too nice to their hosts, in a way you don't find on sites like tripadvisor. You will not get accurate information about the weaknesses of a particular property (like it's too small, the shower sucks, it's not very clean, the pictures displayed aren't accurate, etc). My college-aged daughter stayed at an airbnb in Dublin that had 4 1/2 stars, but was way more hostel-like than b&b like, even though the listing cost over $100/night. None of the reviews said anything negative about the property.
The biggest risk are the beds. They're often bad. If a good mattress is important to you, you should simply avoid airbnb. There's really no way of knowing whether the bed will suck in an otherwise well-regarded property.
A weird quirk I ran into is that hosts can post a translation of their listing into English, but when they do, you don't see the ORIGINAL listing in the local language. This becomes a problem when the host "forgets" to complete all the listing fields in English. In France, I stayed at a property that listed "Breakfast" as an amenity without any mention of a surcharge, so I assumed it was included in the price (at every other airbnb property that listed breakfast, it was always free -- this is afterall "Air BnB"). You can imagine my surprise and annoyance at check out when the host presented me a bill for 8 euros for each (simple) breakfast we had consumed. That's when we discovered that the host forgot to transfer that subject field to his English listing from his original French listing. At a hotel, I would have refused to pay that extra cost, but this is very hard to do at somebody's "home" (who has otherwise treated you well). When I complained to airbnb (they were at least 25% to blame for concocting a confusing system for the hosts), they offered me a $25 voucher, which didn't cover my entire cost, but at least offset half of it.
I will continue to use airbnb, but it will always be a second (third or fourth) choice, when other resources do not produce accommodations that seem satisfactory to me. Airbnb is simply riskier, and I like to minimize my risk.