When you try T2 for the first time it may seem a little underwhelming. Basically it's just a big TV glued to your forehead, and - if you head does not fit Sony's ideea of what a head should be and where your eyes should be located, like it happened to me - you will have some trouble finding the sweet spot to see a full clear image. Wearing glasses didnt help me also, btw.
But it grows on you, and I knew it will, since I used an Olimpus Eyetrek for around 7 years.
A couple of weeks later I was able to find the sweet-spot in seconds, of course I use some straping and extra padding for a more comfortable wear. The only negative is that my overtheear headphones dont fit with this, so I have to use in-ear (through my DSS2 chip - the T2 can do 5.1 but not as good as the DSS2).
The resolution is full 720p, and when you hit the sweetspot you can actually see the pixels (not as much as with the Oculus Rift, but they are there).
It does not fill completely the field of vision, but it looks much bigger than me 50' plasma from 2 meters away (about 30-40% more on the diagonal).
But the quality of the image is better than anything I know of. The colors and levels of black are incredible, and - when watching 3D movies or playing 3D games - there are, of course, no artifacts, so it's the best way, so far, to enjoy 3D, there is nothing on the market right now that offers better 3D quality. Before purchasing I spent some time on AVForums on this matter and people there agree to this.
Again, this is not for everybody. It is simply too expensive, it costed me 900€ which was very hard to explain to the wife - for a device that only I can use and that takes me away from her when I use it.
However, it is a taste of things to come.
When they add some headtracking, improve the strappings (like in that surgical variant), add a little tuning for people with glasses, and make it 1080p, at half price - everybody will want one.
edit - it works with anything that has a HDMI output...
I believe the HMZ-T1 prototype had dioptre adjustment, which was dropped
if they left it in then I would be a proud owner right now..