Pros
KPMG, just like other Big 4, has a name in the industry. Working for KPMG allows one to interact to clients who are prospective employers as well. KPMG also has a good online training program that an employee who wants to utilize these can gain valuable knowledge about a slew of things. At the end of the day, a KPMG employee will have the opportunity to learn as much as the employee wants to learn as long as he/she puts in the time. I also believe that the management is usually supportive of employees who put in the effort to diversity one's skills.
Cons
One downside of working at KPMG is the amount of work required to perform especially during busy season. I think that one's life is literally put on hold because the busy season. Also, while it is firm's policy that one does not eat hours, it seems that management expects one to eat hours. As a firm, KPMG has different practices, and usually these practices are not very integrated. As such, I think it is difficult to move from one practice to another. I also think that moving to another location, although possible, requires more effort to do than just getting a new job at a different firm or company.