Pros
Very subjective pros: Beer fridge, frat house environment, East Coast pioneers in brogramming, work-related parties, work-related after-hours hackathons, work-related dinners, work-branded swag.
Cons
Take the reviews of HubSpot that suggest that hard work and enterprise are the path to success and advancement in context: it depends on the department and your management. That culture is not company-wide, and despite the rah-rah about transparency, most decisions are made behind closed doors, and most job/advancement openings are filled silently because someone pitched it directly to a decision-maker. There's no infrastructure for advancement on merit if you do not play the office politics. If your management, especially your VP-level management, doesn't like you or your ideas, you're not moving. You don't have control over your own advancement unless you have some degree of suction with management. Company culture reinforces that HubSpot comes first; you socialize through HubSpot, you eat at HubSpot, you play at HubSpot, you bath at HubSpot, you exercise with HubSpotters, you drink with HubSpotters. If this is a problem, or if you want a life outside of work that doesn't include HubSpot, company culture reinforces that there are tons of other startups in Cambridge, which is a very, very good point. For Services, morale is bottomed out; people who are staying are doing so for the IPO or because they can get away with a level of achievement commiserate to their pay. Don't join HubSpot for the options, don't join it for the culture, don't join it for the career trajectory unless you already know someone who knows someone already there. Please don't join if you're an introvert. Join if you're an ace at office politics, if you can wrap any level of work in a nice presentation, or if you're interested in marketing or sales. Join if you don't mind promoting your employer and anyone your employer is affiliated with on your personal social media channels. This is a marketing company, no matter what they sell now or decide to sell later--they will sell marketing to anyone. If you aren't interested in marketing, no matter what position you're applying for, no matter how far away from marketing you think you'll be, stay away.