There is one issue on a management server I have encountered several times now:
You need to make sure you have the IPS CRC marker file. If this isn't present, the pre-upgrade verifier will tell you in the report, but if you are doing a Blink upgrade then you might not find out until it's too late. The file is $FWDIR/conf/SMC_Files/asm/crc_marker_db.fws. This is (now) covered in sk175089: https://support.checkpoint.com/results/sk/sk175089
If the file does not yet exist for some reason, you can create the zero-byte file as discussed in the SK. If you ignore the verifier warning and proceed with the upgrade, the database import will fail and your R82 server will be destroyed; you will have to start over with the R81.20 source. Be warned! (i had this happen to a management server, learned the hard way)
Otherwise, gateway upgrades have gone well thus far, and other management servers have also gone well (after accounting for the above warning). Post-upgrade, R82 has thus far performed rather well, which is what I expected. Kudos to R&D on this one!