Pros
Extremely reputable company that looks great on a resume and will certainly boost your career. You have the opportunity to work with/learn from many smart people, and grow your knowledge and skill sets rapidly. It is a sink or swim environment, you own your career and slackers do not have longevity.
Cons
No work-life balance - you're treated as a worker ant and expected to be available outside of working hours and on-call during PTO (this does depend on the project). There is virtually zero effort by the company to retain workers during a strong job market. Turnover is extremely high, leaving a perpetual knowledge gap. Employees with a year of tenure shouldn't be the "old guys"... After some experience, you'll generally be doing the same work as Core counterparts, but at a portion of the pay. What incentive is there to stick around when competing firms are offering 50-100% raises for the same work (ex: Workday, Oracle practices)? There is no discernible culture, no team building events, parties, etc. You go to work to work and nothing else. 401k match is completely laughable at 1.5% vested over 4 years. Lastly a piece of advice to any current or prospective employees - Deloitte will take everything you give them. Find your balance, set boundaries and stick to them. If you start to respond to emails on PTO or take a few late night calls, it will quickly become expected of you.