I wanted to just highlight some of the awesome Surface and Windows RT features ... the Travel app with the panoramas really feels like "virtual tourism", just like Blaise from the Photosynth/Bing team described years ago. It's like a bloody window in hi-def, you can move it around 360 degrees ... so cool ... the wife and I were both just delighted.
You simply have to spend a bunch of time playing with the multi-touch and Start Screen and all the applications to really "get" semantic zoom - it's fantastic. Some apps do it better than others, but the whole concept works great with multi-touch. The animations in the apps are great and in IE for example, the divs bounce around and it's just fun to play around with bouncing stuff around. Try "pinning" down part of the app or Start Screen with one thumb while pushing things around with the other thumb ... try moving an app tile with one thumb, by positioning the Start Screen over the thumb first, then hold, drag up slightly, and then while holding the tile down, semantic zoom out, slide the screen, zoom in, drop ... lots of fun, works well, but takes a bit of practice.
I'm literally learning new ways of using the different modalities every time I play with it. Combined with the Kinect and Smartglass, you have the option of switching back and forth between gestures, touch, and voice - and/or keyboard and mouse and/or Xbox controller. I find myself switching a lot and it's becoming more and more fluid to do so.
I am truly blown away by the Surface hardware. Any performance issues I've heard about, I haven't really experienced except when data is loading in some applications that haven't implemented progress indicators as well as others. Sometimes IE does freeze up a bit on certain pages, but less than IE9 ever did ... it's not often a problem, but not perfect. Sometimes things slow down a bit because you tend to leave apps open, but I am surprised at how well it works to just leave things running. If things get slow in one app, I just flick the left thumb to switch apps and do something else for a little bit and go back ... if it's still hung, I close it. I've only had to use Task Manager to kill a process 3 times since I got the Surface a week ago (and those problems were mostly with Word and Excel and once with IE that I had to kill it).
Xbox Smartglass is fantastic, and I see a lot more potential. Some of the features are not as discoverable, like being able to search YouTube with the keyboard on the Surface - that's because YouTube made it hard to find out how to pair the devices. But it is possible in fact to do that. You can, however, type directly on the Surface to control IE on the Xbox and use Surface as a touch pad to control the browser with multi-touch. So you should be able to use YouTube outside of the Xbox YouTube application just fine (but I haven't tried yet).
I'll try to find time this week to give a full report on //build/ (which was awesome), but I'm catching up at work after paternity and the trip to build, and we have a hard deadline to meet, so I'm swamped with work (and my newborn). Let's just say for now, that I haven't seen Windows devs this excited in a long time ... and I haven't been this excited about development since .NET came out over 10 years ago!
Buy one. Buy two. One for the wife ... she'll want it.