I have a Vaio Pro 13, one of the last Sony models. I bought it over two years ago now. It works very well under Linux. Initially there was a small issue with CPU frequency scaling because it was basically the first Haswell ultrabook, and I had to patch and compile my own kernel to work around it, but that was mainlined after one or two months. I got a version without a touchscreen and I consider it one of the best ultrabooks available, even today.
Reagarding the newer models, I have no feedback yet but I hope they will be fully supported, if not at the time of release then a few months later at most.
I also have two older Vaios, a P (yes, this one http://www.getitnow.gr/MEDIA/content_CustomProductCatalog/m1...) and an EB (17" laptop), which both work well under Linux.
Reagarding the newer models, I have no feedback yet but I hope they will be fully supported, if not at the time of release then a few months later at most.