Pros
HubSpot offers huge freedom for top performers and an ability to aggressively direct your own career. It also offers mostly well-formed roles that can permit "normal" work-life balance. A lot of that is what you make of it, but the key for me is the abillity to work harder and to get rewarded for it. In all roles, that is highly valued over time, and the growth of the company is reflected in the growth of individuals at all levels. Also, it's worth noting that as an organization HubSpot admits to not having it all figured out, and actively wants to improve with the help of all of its employees. Again, not for everyone, but if you're into that kind of environment, you can really flourish at HubSpot.
Cons
Can be overwhelming at first, but if it's a good fit for you, you'll love it. Understandably, it's not a fit for everyone. Management is a lot better at accommodating different work styles today than it was a year or two ago. Can also offer mixed signals with recruiting practices (e.g. beer fridge and ping pong) when reality is a hyper-growth, hard-working job. But I think savvy candidates get this.