Deloitte is a very political company, in order to advance you have to be very chummy with everyone, especially Partners/Senior Managers, they would be your "guardian angels" who would protect you during reviews. Sometimes strong performers are laid off because they didn't establish any solid relationships with Partners/Senior Managers.
Furthermore be prepared for busy season! Busy season is long and not always busy. The client is not always ready and you may have to sit on your hands for several weeks. Seniors vary in quality some are just swamped and will not assist anyone, others will help.
They recent lay offs were very contentious in that management does not communicate criteria for layoffs, this is related to the first comment above about Deloitte being a very political place to work at.