Vantaggi
Avanade is definitely a very collaborative environment with a great office culture (in Chicago at least) if you choose to get involved (would highly recommend). They also offer a lot of great resources in terms of developing new skills.
Svantaggi
If you're coming in as an analyst, your experience with Avanade can depend heavily on your first couple of projects (assuming that you have the opportunity to get on more than one). If you're on a project that you're not thrilled to be on, then you'll find yourself in a tricky situation where if you speak up about it, it might negatively affect your performance reviews, but if you don't speak up, then you might find yourself going down a path that you don't want to be on. This also heavily depends on your relationship with your career adviser and whether or not you feel the freedom to speak up about these issues.