See Whats new for stuff that is really new in 8.2 and RC1, RC2 for specific fixes, for the final it was for the most part Designer fixes for the (dark)theme and some regressions, compared to 814, fixes.
Value lists list display a bit broken
improve some developer icons
investigate switching themes with our own icons
sometimes the designer icon is not found
controller.readOnly not propagated to (all) columns of TableView
Sablo error passing custom type as args in handlers
typeAhead dropdown is not height restricted
Visible tab form loses related foundset when hidden
ServoyDefault TabPanel broken