Well, for starters, something that you have been waiting for for quite some time - New Form Layouts and Style. Besides the existing Responsive layout, RSForm!Pro 1.51.2 gotBootstrap 2.3.2, Bootstrap 3.3.5 and yes, UIKIT 2.22 layouts.
RSForm!Pro already incorporated a Calendar field but it was lacking a time selector. We added a new calendar that incorporates this as well.