Pros
I've been working at airbnb for a year as a software engineer. Top two things I like is how helpful people are. Instead of wasting 2 hours trying to figure it out on my own, if I get stuck, I ask for help, and people spend the time to both answer the question, and explain a bit more so I actually understand what's going on. Within my first few weeks, I was amazed at how much I learned, and now a year into the job, I feel very knowledgeable in my area, and pass on the favor by helping new hires. The second favorite thing about Airbnb is the people. I'm a new grad, and I really like the fun culture, a mix of people who are chill, but also those who like to go out and party a bit more. Nothing that crazy, probably doesnt compare to facebook's epic parties, but I'm more than happy. And it's a great crowd. Also, our office is amazing, just google for "airbnb custom spaces" to see pics. I love bringing people to the office because they always like it. In terms of the job itself, it's very reasonable, flexible hours, only occasionally work late when I choose to, supportive and helpful team. All in all, there's nothing that I really dislike about Airbnb.
Cons
I would definitely say the company has more focus on product development and growth, than on engineering quality. That means that currently the code base is a little messy, and there are times where you'll have to ask a few people before you find someone who understands the code well. However, this is definitely being worked on as we expand, and different components are being refactored or rewritten. Also, I feel that designers get too much say in the things that are built, occasionally at the expense of functionality.