Pros
Accenture's knowledge base is second to none. Additionally -in my experience- even the most senior of SE's respond to queries within 24 hours - even if it is to defer the answer to a later date, which by the way is committed to. The majority of staff are there for a reason: they are articulate, know their stuff, and senior people bring relevant experience to the table. And with the right crowd, there is ample opportunity to adopt a similar "quiet confidence". Lastly, Accenture is a listed company that is accountable to shareholders instead of partnerships. Individual partners have a higher tendency to protect their own turf which typically impairs collaboration across practices and regions. This significantly reduces frustration when doing business development work.
Cons
Accenture has the best people, probably because it pushes them hard and has high standards. And more than elsewhere, it is either up or out. Limited support if you slip, and even the most respected seniors will turn their back to you. The hard fact is that Accenture is -at the end of the day- a consulting company trying to bite off a pie that has been getting smaller and smaller. It cannot afford to allow slack. I would advise anyone to give themselves a good hard bought before considering Accenture: a wrong decision could leave you blistered for life.