Just bought a new XBR-55X900A and love it from hhGregg. All the stores and online are selling them for the same price-the only difference being state sales tax rates They had over 30 in stock so they are available in advance of the reported 5/20 ship date.
Despite numerous posts, the screen picture is much brighter/vibrant and sharper with better color, yet smooth pixel-less for regular network broadcasts. Blu-ray disk movies are improved with sharpness, better color, and a picture that "grabs you", so I do not agree with some posts that the picture is the same as the 1080p TVs. The up scaling is noticeable. Also YouTube is now offering 4K videos so you can see what new source material will look like. Not sure what the new Blu-ray disks with 4K mastering will do for this new 4K TV. Sony provides via mail 3 of these disks when buying the new 4K TVs The biggest improvement for me was the exceptional sound quality and passive 3D. The difference between my 2 year old NX810 and this X900A is remarkable
My sound is better than I was getting using a Boston Acoustics sound bar (w/subwoofer) with my old TV. The sound is very close to my Bose system. Very happy with the new speakers. And yes my 55inch takes up by 60" entertainment center space or I would have purchased the 65" TV. But I am happy with the new speakers and the fact they are attached makes for a good looking TV. My wife is very happy as the new TV looks great with her furniture instead of a sound bar popping out of a wall or corner. These new speakers produce an exceptional sound better than any Sony TV I have ever had including those that had front mounted speakers. There are 6 speakers with a total 65watts
The 3D is exceptional, as good as a movie theater with great 3D depth and a brighter picture (my 2 complaints with the NX810). Much better depth and much sharper than my previous Sony TV (NX810). Also the simulated 3D is also good. And the passive 3D is easy on your eyes. Just watched Avatar 3D and my eyes are not tired as they would be with an active 3D. 3D is now worth watching and the glasses are light on your ears as they are only a thin plastic (no batteries)
Price is steep but happy with the purchase
Also Sony provides three free Blue-Ray Mastered in 4K disks. See www.sony.com/RegisterMy4K
Also the new Sony BDP-S790 blue-ray player upscales Blue-Ray to 4K and passes it to the X900 via the new hi speed HDMI cables that are available for under $10. My X900 display data reports a 4K signal received when using a normal Blu-ray disk so I am hoping the new Mastered in 4K disks will make a difference (vote still out). But YouTube also has many 4K videos available that you can stream via the YouTube app. This app makes it easy to shift the YouTube video from your iPad to the X900 display and the video appears to be 4K-certainly much better than any of the YouTube HD videos.