I like most of what I'm seeing. However, I find the color scheme to be kind of nasty. I've always preferred dark-colored devices, for the most part (unless I can get a cool color like orange or blue). I find light-colored metal really ugly (though I loved my Zune HD 32, I wished it was the dark color of the 16-GB model). Basically, if that center-back color was it for the whole device, I would like it more. I'm also 10% against that gold/champagne color on the volume side of the device.
From a hardware standpoint, I like the looks of everything but the edges. I don't like rounded edges, not sure why. I think part of it is how the third color accents it in a way I don't like, but I also like the hard lines of the Icon/930, as opposed to a tapered/rounded edge, like my 920 has. If it's hidden with a unibody/single-color shell, it's easier to tolerate.
The UI of the OS looks pretty good for a Windows Phone follow-up, though it's not what I'm expecting from a hybrid OS like Windows 10. It's visually good, but it just seems like something we won't be getting from Microsoft.