There should be no problems upgrading from 2.1.2 to 2.2.0—no features were removed and none had their classes changed.
.label's are now display: inline-block. In my particular usage, I needed block in one area.
tooltips used to default to html: true and now they default to html: false - The issue with this is that popovers are now html: false as well. I think popovers should default to html: true given their nature.