Pros
Generous healthcare benefits (full medical/dental/vision), a 401k with matching, a bonus program, flexible PTO, office snacks, nice offices, catered lunches, offsite happy hours and hosted events, intramural team activities, enthusiastic and curious colleagues who are usually open to collaboration. You get out what you put in, so you have the potential to learn a lot.
Cons
It's unfortunate, because at first you're blown away by their integrity, and feel connected to their mission of disruption in the Telecom industry. But pretty quickly, you'll find there isn't much substance behind their goals.
Their core values are just vehicles for giving your friend a public hi-five, the culture is gossipy—I constantly hear people speaking negatively behind each others backs, and their "perks" feel like bandaids on top of an actual problem. If you don't attend their social events, you're looked down upon and seen as someone who's not supportive of their culture. Also, there's a constant feeling of being watched which could potentially lead to your dismissal.
An entrepreneurial spirit is a welcome addition, however putting in the extra effort doesn't amount to much. There's limited to no opportunity for advancement. Also, besides titles, there's a general lack of systems and structure.
Finally, there's massive turnover and there have been multiple failed attempts to scale...at some point it leaves you wondering, are the employees the problem or the employers?