My actual deliverables are pretty fun to work on and involve interacting with lots of different teams and clients, so the experience has been pretty good thus far. The people on my own team have been great to work with and all seem to really care about the job. Product people have been great to us and Engineering has been accessible throughout.
Cons
The position wasn't perfectly well defined when I first joined the company. I also have zero insights into any room for growth possible. The team is much smaller than previously and the company seems slightly cheap.
Everyone has an equity stake and I don't know if that's the secret sauce that makes everyone so aligned and the politics so low - but everyone is super-aligned on the vision of revolutionizing marketing and there's hardly any politics. It's a true meritocracy as far as I can see in terms of the biggest contributors getting the quickest advancement. MediaMath's also big on training - NMI and Marketing Engineering Program are industry-leading.
Cons
The work-life balance isn't always great. Don't think you can beat Google without some long hours!