Windows Phone? No thanks
My 15 month old Galaxy S2 has specs not far off this and with Jelly Bean is as slick or slicker in terms of polish. Not to mention not being totally locked down, and with more and better apps.
Also, am I the only one that doesn't like Metro? I find it inefficient and clumsy. It wastes lots of screen space and e.g. the all apps list is a pain to navigate. Once you get past the tiles (which are nice, granted) it's just not very good.
One of my coworkers has a Samsung with WP7.5 and we have tried racing to do various tasks and the SGS2 generally has won handsomely, that is if the WP phone can do it at all (case in point: try emailing a PDF that you've just downloaded from the web. In Android it's Share->Gmail from the Adobe Reader app, in WP7.5 we simply couldn't figure out how to do it, the Adobe Reader app has no share function and WP doesn't let you near the filesystem to do it manually.)
If this is an example of a typical WP8 launch phone then I'll be sticking with Android for my next phone.