It's a "new feature" - we'll see how it goes, an take it from there. There's a 1MB limitation for file size to keep things somewhat under control.

I'm not sure you'll be able to include images within posts with this specifically. However, one can add an attachment, and then, once they have the attachment URL, embed the image with the img tag using the attachment URL. Those too, are limited to 1MB for sanity.