Sketch 51 is finally here with Library Styles and some more... https://www.sketchapp.com/updates/
Already installed. Feels snappier, not sure if it's just a placebo effect or not, too early to say. From my short list of plugins only one – Keys for Sketch – is incompatible. Craft, Paddy, Overflow, Rename-it, Instance Renamer, Looper and Mockuuups are not listed as incompatible, so they should be good.