I bought a new X1 Yoga 3rd Gen a month ago - my first new ThinkPad since since my T23 company purchase in around 2002. I needed a newer machine for work, my W520 could no longer handle the latest eye tracking software I needed to run for my work. I also needed something a bit more portable that I could walk around with while tracking people in my research so opted for the Yoga format. I have to say I am impressed overall with the machine. It's fast, handles everything I can throw at it, and has flexibility (literally). I use it in tablet mode when walking around, then laptop mode when processing/viewing data. I don't feel it has the toughness of earlier T or X series machines, but overall, I'm happy with it. I am learning to use USB C (oh well, what to do with all the older X220/T420 chargers I keep around the house). Right now this machine is dedicated mainly to work projects, and my T420s is still my daily desktop machine in a dock with twin monitors, and my X220 is my classroom machine for teaching, as it gets banged around a lot. However, I think the X1 Yogo will be my travel machine in the future, light and easy to use.
In my reading up on the X1 Yoga before purchase, there were a lot of complaints about heat and CPU throttling etc. By the time I bought in Feb., it appeared that most of the issues were resolved via latest BIOS updates. When I do eye tracking, I run it on battery with "best performance" and it seems to be true to the settings. It does get a bit hot, but it is working hard at that point. The screen performed beautifully with my software. If this form factor meets your needs, and you want to spend a couple of grand US, take a look.
Current: 2 x W520 ET, 2 x X220 i7, T420, X230 i5, T420s, MacbookPro, Dell Venue 11 Pro, Dell XPS 8930, X1 Yoga 3GEN
Past: IBM5150-8088 500 600E 600X T20 T21 5xT23 X30 3xX31 X32 T40 T42 3xT43 T43p SL510 T60p X60T X60s T61 2xT400 T410si T400s T500-3.06GHz X200 X201 X220i5 X220i7 2xT420s