Pretty good. Many new features, one of them being non-destructive filtering which is the ability to apply a filter (say a Gaussian blur) and then re-edit the filter parameters or even remove it without having to undo.
However, at least for me, some changes will take some time to adjust to such as “OK” and “Reset” buttons of dialogue boxes now being displayed at the top rather than the bottom.
Also years work of changes without the wider public testing them means that there are a few bugs/annoyances, one of them being the checkerboard pattern for transparency being replaced with a solid colour (equal to the background colour) when you zoom in too much.
That was probably a release candidate you were thinking of.