Saw this over at ZDnet:
A hasty move to Google Apps a “˜career-limiting move’

Perhaps the most interesting thing is that some consultancy managed to write a 55 page document on what is quite an obvious and well understood area, but I think the main points apply not only to Office (thick client) and Google Apps (web based), but to the whole area of server sided apps in general.
One of the main factors being:

>> Power users and sophisticated documents are not supported

But maybe this can change over time?