Pros
Relationships - atom42 is a place which doesn't make you have a 'work' and 'home' identity, you're completely free to be yourself. Because of this you end up having great relationships with the people you work with. I've worked at the company for over 8 years, and now I'm working with a lot of my best friends. Progression - at atom42 they never hire above as they really want to challenge all new recruits to build up their skills so they too can become directors at the company. If you work hard, you get rewarded for it. Authenticity - It's one of the company's values but they stick to it. The company is totally transparent about where it's at, and also with you as an employee. This means you too get to be totally authentic and give and receive feedback openly. It really makes you trust the place, and the people you work with.
Cons
At atom42 you're trained to do the whole role, from SEO, PPC, UX, Social etc. Everyone has multiple skills and you're required to have or learn a high level of each. Some people may be put off by this if you wanted to specialise in one area of marketing, as that's not what the company is about.