This should have been the way, always, that firmware, or device software, get upgraded. You just do it, and it should just work. The upgrade process should test that everything is good to go, and let you know if anything is amiss, before commencing the upgrade.
In the unlikely event that something does go wrong after starting the upgrade, there should be some automatic rollback, returning the system to its original state, leaving the user with no more than a small annoyance that the upgrade did not happen.
Unfortunately, my experience with pfSense hasn’t been so good. By and large, everything about pfSense has been good, operational-wise. It’s just that I’ve not been very lucky with the firmware upgrades.
Version 2.2.1 is a minor upgrade. There are a number of security fixes, but none terribly critical. The recent SSL FREAK vulnerability doesn’t affect version 2.2. However, there’s no reason why you should skip this version either. If you’re running pfSense, just do the upgrade. I’m beginning to have more faith in the pfSense upgrade process!
Read more: pfSense 2.2.1 Release Announcement