We've added a Lenovo ThinkPad X1 Yoga 4th Gen Hands-on video.

Comparison to the X1 Yoga 3rd Gen:
  • Thinner & lighter design (just 200g more than the X1 Carbon 7th Gen)
  • Decent ports: dock connector (phew), retains the Full HDMI, 2x USB
  • Easy to open for maintenance (for the M.2 swap)
  • Excellent warranty options
  • More display options (inc Privacy, 4K UHD, etc); brighter base display option (depends on your region)
  • Brand new 4 speakers design (unusual for such a dramatic change)
A direct competitor is the Dell Latitude 7400 2-in-1, HP EliteBook X360

Other notes: 
  • The keypad is still good (marginally thinner travels); smaller touchpad/click buttons take a while getting used to.
  • Webcam functions - although don't throw away the conference camera just yet
  • Port layout & fan placement direct some heat to the right-hand users
  • No more MicroSD card reader
  • WWAN/LTE only available on some models, cannot be added after purchase
  • Ram, Wifi module, CPU is soldered on
  • Could consume a lot of energy on peaks load at around 65W (battery shrunk to 51Wh)