I've discovered a few of these on my own. If you have encountered or read about limitations I haven't, please bring them up and I'll try to expand (or contract) this list with new information.
Here are some I know of:
- Marker Animations (no plan for support soon)
- Heat Maps (last I checked anyway)
- Polygon editing (although I worked around it)
In the case of polygon editing, you could set a polygon to "editable" and the map would display polygon editing UI, and the polygon would change, but you could not access the data related to the new polygon paths to save it. I have submitted a pull request with a working fix for this but not sure it will get integrated to master.