Some of the game devs I follow on Twitter had a couple of things to say about AWS.
They seemed mostly dubious about it. Both about the source code aspect of things, and about whether it would still be maintained in five years.
Twitch integration seems like an original feature. Cloud integration, and most of the features they mention seems tailor-built for making free-to-play games though.
I dunno, Amazon is pretty new to the game engine market, I'd say wait and see more than anything else, it's in beta, it's at the stage where they can show bells and whistles but we've no idea how support will work in practice yet, how they will behave regarding the games made with their engine. They still have some issues to sort out (I read a post from a game dev stating that his games had been uploaded on their app service without permission, and Amazon had done nothing to remove them), before I'd trust them.
It does have a couple of well-known game devs with a very good resume working on it (like Patrick Wyatt, for instance), so they must have trusted Amazon to be doing things right.
Just speculating for now...
On a side note, clause 57.10 is weird. Viral apocalypse ?