Pros
You will work hard, but learn a lot. This place really launched my career and I am grateful for that. It's great to be part of a team that is driven and is considered to be the best in the industry. I had the best co-workers and a fabulous manager. I can't speak for others on glassdoor, but my managers (VP level and C-level) always cared about my career growth and were understanding about my work life balance when I needed it. If you have a strong passion to do well at your job you will do well here.
Cons
You put in a lot of hours. The benefits could be better. There is a lot of turn over which can be frustrating when trying to get projects done. Approval processes can be painfully long. I always told the people I interviewed to work at Inovalon that you had to be a Type A personality. If you aren't driven to succeed in your career this is not the place for you.