Pros
There are upsides - Accenture is a powerful consultancy, and as an Avanade person, you will typically see the insides of a lot of Accenture gigs that are often underway before you got there. If you like working with Microsoft technologies only, and can coexist with other technologies without acting like a child about it, you'll do well. If you're a Microsoft bigot, you'll find that Accenture senior leadership will not enjoy having you around. This is a good place to learn how Microsoft integrates with the rest of the world, and where you can burn your single life free time.
Cons
Remember work/life balance? Forget it. You get on a gig, an Accenture gig at that, and prepare to hand your life over (and hope your pay and bennies are worth it). Also, when you're working for Accenture, you're a subcontractor, no matter what level you get to. Get used to that idea - since they'll remind you of this all the time, and you destiny is often theirs. And keep one more thing in mind - your career manager at Avanade will make or break you. If you get a weak, non-people career manager (America is teeming with them) then you might not have anyone to speak up for you at promotions. If you're not a career manager within your first year or two, promotions and bonuses will remain a mystery you 're locked out of. If you're not well liked by a senior career manager, you can be frozen out of career opportunities if your career manager or others in the room don't speak up for you. In the last few years, promotion group-think prevails.