Pros
I recently left a later-stage software startup to join BookBub. These kinds of moves can be hard -- essentially you're taking a leap of faith. Even if you do all your homework, you never *really* know if you're making the right choice. I'm very happy I decided to take my BookBub leap of faith. The company is at a great stage right now. It's still small (~30 people), but it has product-market fit (loads of paying customers and rapidly growing revenue). As an employee, that means your work is all about building, scaling, and growing -- not searching around in the dark for something that works. A good objective way to see the company's traction (and its potential) is to first look at the comments from users on BookBub's Facebook posts, then to do a Google search for BookBub and see some of the testimonials from authors who have used the BookBub service. I made up my mind after I did that. Finally, the most important thing: It's a great team. The management team is strong and has diverse skills and experiences, and the whole company is filled with smart, energetic, passionate people. I'm learning a ton and am super-optimistic, if you hadn't noticed :)
Cons
It's an early stage startup. Lots of the services, systems, and processes that you might expect at a larger company don't exist yet.