Pros
Overall this is a great company to work for. It is clear that a lot of time and thought is put into what is best for employees. The most notable pros for me include the highly flexible work schedule and unlimited time off. HubSpot also makes a massive effort to provide tools to let employees work in the way that works best for them.
Cons
While it is a great company, overall it feels very "young" both in the time and the age of most employees. So if you are used to a more structured environment, it can take time to get used to the company culture. Additionally, decisions take much longer than expected, limited process documentation and there is no phone number to call for technical issues making it more difficult to resolve. Career advancement path and annual compensation structure is unclear.