Pros
From my interviews (2 years ago) to now I have thoroughly enjoyed every minute. HR made me feel very welcome and helped me feel at ease coming into a potentially daunting environment (having never worked in Media before). I have also had the opportunity to work with a number of other teams (NMI, OPEN, Engineering, PS etc) both UK and US based who have all been very professional and a joy to work with. The office environment is fun to be a part of - who can argue with an arcade machine, vending machine and endless sweets / chocolate? I enjoy the fast paced nature of the Media Industry and being on the edge of integrating with new technologies.
Cons
I would have said the on-boarding process as it can be daunting if you haven't worked in Media before. However, MediaMath have recognised this and have really focused their attention on improving this for new joiners.