Pros
Like-minded co-workers who will typically share the same frustrations with the company as you. If you're lucky you might get a $20k bump in pay if enough people leave that week.
Cons
The development team is a sink or swim environment and I'm not speaking about the code, I'm speaking about the leadership. They'll either love or hate you. However, they'll very quickly turn around and promote you and / or give you a raise if one of your co-workers leaves, even if you were days away from being fired. You can't deny it's a bit concerning when in the matter of a month 5 employees leave. The five people who left were all recently promoted and / or being groomed to be promoted. All had been with the company for over a year and were hard working developers.