Sony Ericsson better have a very good answer to the question, "Why would we buy this when we can play mobile games on our current Android phones?".
Having been involved in this one a little bit, I can safely say that even if their eventual catalog is not stunning, having gamepad controls makes this an excellent phone for emulators like snesoid. ^^
I think the draw here is having "real" controls, which for some types of games just work a lot better than emulating controls with slick touchscreen displays -- which require you to obscure the content your interacting with with your hands and on-screen smudges.