Pros
Simon's got a lot going for it, but more than anything it's the group of people it's brought together. I genuinely enjoy the company of pretty much everyone I work with, which is hard to come by. Everyone's smart, driven, and friendly, there's a lot of work getting done, and it tends to be heavily cross-functional, which all means there's a lot of learning on the job. Aside from the culture and the people, the product itself is really strong and has been a first-mover in a fairly new category. The company's also well-funded and increasing headcount rapidly. All of this makes for a really exciting time to be here and the energy across the company reflects that.
Cons
Nothing too significant comes to mind. There's the standard challenges that come with startups; especially a startup that's at an inflection point in terms of maturity - less structure, more ambiguity, occasional inevitable missteps that come with rapid growth. These can be frustrating at times, but on the whole the experience is positive and there seems to be a pretty genuine desire from the top to address any issues.