Pros
Illumio allows the IC to cut a path and build out their role. There's a great deal of autonomy with a huge focus on individual accountabilty. In other words, it's all about delivering. It's not your typical start-up trying to find it's way...there are very experienced players from diverse backgrounds as well as recent grads which lends to an amazing synergy of talent and know-how. It's an exciting place with an amazing product and a huge opportunity. Management appears to be in synch on an operational and strategic level. They're not afraid to ask questions and they know where to get answers.
Cons
A lot of rigor you'd normally see in a company much more mature which could become a blocker or could serve the team very well. Really high hiring bar, hopefully not overlooking unobvious talent.