https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=886998
Quoteintel-microcode: regressions on Haswell, Broadwell (crashes/reboots) and Kaby Lake (sleep-to-ram)
No problems here for me. apt-listbugs gave me the heads up and I did (as root) "apt-mark hold intel-microcode" and I will wait and see.
Systems that are sparky testing or debian testing for me are both intel atoms and are supposedly immune to Meltdown and Spectre. So one update I can really wait on.
Debian BTS now says it is fixed.
apt-mark unhold ## for me.