As for UI themes, it's never been a priority feature for me, but I remember someone pointing out several years ago how useful it would be for sight-impaired users, so I've been on board ever since with the idea that it's valuable to the user base, if not directly to myself. So glad it's now coming.
And I do find, now it's coming, that I look forward to doing a bit of decorating. I spend all day every day in Sonar, and it could certainly do with some cushions and house-plants.