While portability is not as good as the SP3, it is still very good. The chassis is nice and compact, and the build quality is superb. I have to say that I am very satisfied with the computer. It is very fast, and there is no lag in navigating the UI.
The real tipping point for me in choosing this machine over the Surface Pro was that I knew I would have to produce a lot of content in a wide variety of places, often without access to a good work surface for a wireless keyboard. The keyboard on the Spectre is outstanding for a laptop. I have spent roughly 25 hours typing on it and I am very happy with it. The 360* hinge is very solid, and I enjoy using it in tablet mode. While it is heavier than other computers in its category, it is not uncomfortable to operate as a tablet. I have had a lot of fun playing flash games like World Wars 2 and Bloons.
I bought a dell active stylus for $50, and the functionality for taking notes in One Note is pretty much the same as the SP3.
Overall a very slick computer, and it was cheaper than the SP3 with similar specs. I would have been very happy with either one, but the great keyboard is the dill sealer
Spectre = 5th gen i7, 8gb ram, 256gb SSD, $1150, plus extra for an active stylus
http://www.microsoftstore.com/store/msusa/en_US/pdp/HP-Spectre-x360-13-4003dx-Signature-Edition-2-in-1-PC/productID.316333400
SP3 = 4th gen i7, 8gb ram, 256gb SSD, $1400, plus extra for keyboard that is not as good as the spectre's
http://www.microsoftstore.com/store/msusa/en_US/pdp/Surface-Pro-3/productID.300190600