Pros
You'll love the people you work with, or at least I do in my department. It's pretty hard to get into HubSpot, but once you're through, you'd see why. The calibre of the people here (smart, helpful, driven, etc) is pretty outstanding, and it challenges you to bring your best as well. There's a lot of openness & transparency, and it's a place where employees are empowered. Our employee perks are pretty amazing too!
Cons
I wouldn't say this is a con per se, but because there's so much of a start-up culture, and new things are happening all the time, sometimes it does feel like you're building the plane as you fly. Great if you like spontaneity, but if you're the sort that needs structure and defined guidelines, you do need to get use to it