FYI - Windows 10 versions of the Yoga Book are starting to show up around $250 as well. I picked one up (in addition to the Android model I already have) a few weeks ago, and have been very impressed with the performance. I can run the following with no lag or issues (real world example)...
- Edge browser with 5 open tabs
- Opera Browser with 7 open tabs (one of which is actively playing a YouTube video)
- MS Word two 10+ page documents with heavy formatting) - full version of Word, not mobile
- MS OneNote (Full version)
- MS Mail and Calendar apps
- File Explorer
- And, Task Manager, Malwarebytes AV, and iCloud services running in the background
This puts the memory usage at 94%, and the CPU at around 35%, but the machine is very usable (I am typing this on the Yoga Book while all of the above apps and processes are running).
I also like the fact that Windows will continue to get updates on the Yoga Book. Whereas, the Android Yoga Book will likely stay right where it is (i.e. no OS or security updates).
@sracer has done a really nice job of covering the Android version of the Yoga Book, so I just wanted to share some thoughts on the Windows version for anyone interested in this rather unique tablet/ultrabook.