Pros
The opportunity to solve cutting edge problems with incredibly intelligent people. Rapid growth and innovation means there is never a dull moment, and you can rise extremely quickly if you have the chops and are willing to put in the work. The company encourages frequent cross-functional rotations, so you can gain a diverse skill quickly. The matrix environment allows employees to gain a technical, diverse skill-set that is applicable to most tech companies. By far the most exciting place I have ever worked.
Cons
The frequent growth and belief in running a lean organization on darwinist principles ("if they can't manage a huge amount of responsibility with a small team, we don't have the right people") leads to constant turnover, long hours, and sometimes unfair expectations. The emphasis on intentionally rotating talent compounds this problem. Sometimes it feels like the company is placing too much emphasis on broadening its scope, and not enough on solidifying its base. Extremely technical environment with minimal documentation for some critical systems and functions, which results in inefficiency/misses, and an aggressive learning curve for many positions.