Pros
ZS has a community of smart individuals that work together. There are inter-office teams for projects, which means that you have access to the whole ZS network throughout your tenure here. Additionally, the smart travel policy at ZS ensures that employees are doing quality work, rather than solely focusing on pleasing clients. There is great room for advancement, as the company is rapidly growing. Transfers between offices are common, and easy, and the chance to have an MBA paid for by your employers is also pretty great.
Cons
Long work hours, but that's the same for any consultancy (in my first year, averaging around 60 hours/week). Fractional staffing model puts you on multiple projects at once, which can be both relieving in a change of pace and confusing as multiple deliverables and deadlines occur without coordination between managers.