Pros
At least in the early years, you're surrounded by peers in your demo. You make a lot of friends who have similar interests, passions, and are in similar places in life. This decreases, though, the higher you ascend the ranks. The comradery ends quickly after becoming anything higher than a Senior.
Cons
Most people don't live to work, but the culture here, and at any Big Four, is that you're not likely to ascend the ranks unless work is the center of your life. Look at the number of Senior Managers and Partners with multiple divorces or aren't married at all. Their claim of work-life balance is that they bring their kids to firm events. The firm is the center. People with any sort of desire to have a life outside of work leave within a few years, so all that's left to run the company are, on the whole, the worst type-A automatons imaginable. They're fierce and unforgiving and have little tolerance for even the most inconsequential mistakes. It's an accounting firm, not a military regimen. If your sole purpose in life is to sit in a 5x5 cubicle to find every last cent, yeah it's a fantastic place to work and you'll fit right in. Otherwise, take the 2-3 years of connections and experience and run.