I have been using the Preview 3 (I believe) for a couple of weeks. Since I teach web and interactive design, I have had students download it in class and play with it. It is so similar in the interface to Flash that it was simple for them to pick up-- and the program does not have many features so it was a no-brainer. Students seem to sort of get it. Instead of just talking about HTML5 it is nice for them to have a tool that they can manipulate and see the difference.
A couple of common problems. When saving out the final files from animation created within Edge from scratch, I had one file (out of 20) that Edge added some slashes to the font names so the font-based animation wouldn't run. It was easy enough to go to the code side of the resulting HTML page and delete the extra slashes and recover the font names so it them ran ok. Of course I had to do it--- and the student had already walked out of the class ticked off that his time invested seemed to be lost. Ah the impatience of youth.
On pages that start life as HTML files with CSS and graphics, I noticed one page fell apart and looking at the code side, several end-div tags were deleted. I went back into the HTML page and replaced the end divs-- I think that three seemed to be arbitrarily deleted. They weren't all divs that were affected by the animation, but included my container div. Once replace the page still animated fine and the structure returned.
I use a simple web page as a demo: [url deleted by host]