This is a MUST HAVE for serious web animators.
It's FUN, which is more than you can say for Bootstrap, which overrides your CSS themes. This just provides an easy way to manipulate your CSS - rather like JQuery (which it is built on) it allows control of the DOM.
It does anything you can do with 50 lines of JS or CSS in just one line of JS. It moves, rotates, scales, all manner of DOM objects (text, images, DIVs) effortlessly. Eases made, well, easy you could say! Drag/drop is a breeze and the scrolltrigger feature's a beast.
Great product, great support - they're not paying me to say that, in fact I paid them $90 and it was money well spent!