Pros
There are a lot of great things about KPMG: Many different opportunities, fast-paced and challenging work environment (in a positive way), good people (generally) to work with. If you like to be challenged and you like accounting, KPMG is definitely the place to be...the work environment is definitely not stale or boring.
Cons
Work/life balance often doesn't exist; the advantage is the flexibility, but you still have to work the hours. I think this is true at all of the accounting firms, so no real surprise here. The technology available isn't that great and definitely behind the times, so a lot of time is spent dealing with "paper" (priting, reprinting, copying, etc.)...shouldn't have to spend that much time with paper in this electronic age.