Where to start..
There is a massive issue with cliques and favouritism in this company. If you are lucky enough to get a job here, it's more likely due to having friends who already work at Unity rather than getting employed based on your actual skills and experiences.
Hard work is not in any way rewarded. Even if you go above and beyond expectations, you don't get any recognition for the effort you put in. If you are a talented newcomer to the gaming industry, do not expect a lucky break at Unity, your talents are expendable here. In my case, contributing my time and skills to more than one area of the company amounted to absolutely nothing, not even a permanent position.
Special treatment is given to unsuitable employees far too easily. I have seen employees have worked for Unity for years and gained substantial experience over a period of time then someone new joins the company with no industry experience and gets pumped up within a short space of time based purely on their social status within the team.