Just finished installing on a (fairly old- mid 2010) spare iMac.
Download was 4.8GB, installation took about 45 minutes or so. One worrying moment near the start; a long tone from the speaker and the display blanked for long enough for me to start worrying. But then it rebooted and carried on. Probably updating the NVRAM or something.
No other issues. Looks exactly the same as it did before, but About this Mac
says it's running High Sierra
and Safari has an Autoplay
control in prefs so presumably the install worked
Haven't done any real testing as there's not much on it. I'll update this machine when it's more convenient.