Heh, I'm guessing by the fact that you're cheering your first day of busy season that you're a first year? Good luck. I'm still in big 4, but transferred two years ago to a custom modeling group that has no busy season. Don't miss audit at all.
Toward the end of my first busy season, I remember watching a girl sitting across the conference table from me just break out in tears, and run out of the room. Turns out she ran to the manager of the project and basically told her she was on her way to HR to quit. Granted this isn't the norm, and that client was particularly bad with quite a few issues. I only had a couple weeks on that one as I was pulled on after my "main" busy season client. We were easily pulling 80+ hour weeks on that one, and I'm guessing working two months without a weekend finally made that girl snap.
That said, I'm sure you'll be fine. Good luck with your first busy season. Your client really makes or breaks your experience. For the most part (excluding times I was pulled in on clients like the one above when extra staff was needed), I was assigned to the same clients for my busy seasons, and I was really only doing ~60 hours.
