Was going to try it, but now that I'm running off an SSD, I don't fancy wasting the write cycles that would come with reinstalling everything once the trial period runs out. It's also not so easy to get the preview access in the UK, although there's a workaround to make it show up in the store (I got that far).
It looks good to me though. I like the fact that you can have the same wallpaper for start-screen and desktop environments (should have been in 8.0 really). Also, now that I'm back using IE after many years of giving it a wide berth, the performance gains in IE11 sound good. It's using the GPU for a bit of acceleration, and to smooth out scrolling etc. - apparently a 30% speed increase.