Pros
All the cultural pros have been covered by everyone else, this place is amazing, the people are awesome.
As a backend SWE straight out of college working for HubSpot for about 8 months now I want to point out my most important pros so far so I can help other college students make an informed decision
1. You will learn, and you will learn a lot. HubSpot doesn't just have a great culture, it has an advanced technology stack. The code base is very new (even at its oldest points) and we utilize a vast array of technology. Your resume will be very impressive after being here for just a year. Your bosses are very supportive, and will make sure you are learning from every pull request, and every mistake. You're encouraged to take your time and develop your skills, I have never felt like I wasn't being supported by my team during my ramp up process. Everyone around you is very intelligent, and you're able to just absorb information and knowledge. You'll get a bunch of different opinions (HubSpot engineers are very passionate), and it'll be up to you to draw conclusions and decide what the best path forward is. You learn by doing, and you do a lot here.
2. The infrastructure is state of the art. Unless you're on the dev ops/infra team (bless them), you won't have to worry about deploying/scaling/monitoring your teams' service, it just happens automagically. Your team has a mission that is well defined, and you will pretty much only be writing code that adds direct value to that mission. This allows teams to iterate very quickly, and is honestly one of my favorite things about working here.
3. Autonomy. You will absolutely not be micro managed. Do you think this new technology that just came out will help the team? You have the freedom to pursue that. There is no set work schedule, nobody to track your hours, if you're executing and doing your work effectively, how you manage your time is up to you (meetings are generally from 11 AM - 3 PM from what I've seen).
4. The relationships between product managers and software engineers is absolutely phenomenal. All product managers I've worked with are surprisingly technical, and understand that what may seems simple to the lay man, may actually not be quite so simple, and will respect our estimates and feedback. The product managers also do a great job communicating what the customer pains are, and are a great bridge between us and the customers. I always feel like the work I'm doing has a purpose, and is directly adding value to the company, and this is largely thanks to the wonderful PMs we have.
5. Wide variety of roles. We have backend/front end teams. Within those teams we have dev ops, infrastructure, platform teams etc etc. You have the freedom to pursue what you're most interested in and where you take your career is really up to you.
Cons
Experiences may vary from team to team. Sometimes the infrastructure is too "magical", meaning it can be tricky to grasp and understand.