Pros
Very cool company that is truly going places. The software is excellent and the C-level guys are very transparent about everything from financials to where they envision the company to be in 5, 10, 20+ years. They recently added a much larger fully stocked kitchen and they do make other attempts to make the work life more enjoyable.
Cons
If you are in sales, it is extremely stressful. You should just wave goodbye to having a life, because your life from 7am to 7pm is now 100% HubSpot. The monthly quota is very difficult to meet, and if you have four months sub-quota, then you are at risk of being put on the performance plan. The turnover is high and they recently made it more difficult to get promoted. Also, they try to sell the "no vacation policy" as an opportunity to responsibly take unlimited amount of vacation. However, since you are on a monthly quota, you basically find yourself NEVER being able to take vacation. Fortunately, they recognized this. But the way they combatted this was by increasing the monthly quota and saying once you've been there for a year then you can take two months at 50% quota (and still get paid 100%...if you hit your number). Ask about 80% of the sales reps there, and they will tell you that this job is insanely stressful and will take over your life.