I upgraded from a NUC 5i5 to this 8i5.  First thing noticed is that it makes no noise!  The fan was always revving up on the old one.  It was easy to install new DDR4 RAM and the m.2 drive from the old NUC and the system booted up fine.  Just needed to re-activate Windows and install new drivers.  I was up and going within 30 minutes.  Hopefully it will last another 5 years like the 5i5!