Pros
Fast paced environment where you can gain many new skills. I would Only recommend that you accept a position here if you seek new skills and are not picky about the company overall. There can be opportunities to move around which is a pro. You will have to hit the ground running. You will likely not receive much training. The company is often described as "sink or swim." Stock bonus $ is nice but you have to be there for 15 months before you start seeing any of the $. Bonus will likely be less than is presented in the offer.
Cons
It is a negative culture. I was at the company full-time for 2 years. Overall it is not a culture where employees feel valued or supported by management of any level or co-workers. There were Many dissatisfied employees when I was there. Benefits are limited and pay and bonus are below average. You are not rewarded when you should be, for example when you switch teams and take on a new role (even if it is a lateral move) in my opinion you should be rewarded. Those are just a few of the problems with Zayo.