When the Popup control is attached to the page, the "Top" and "Bottom" options of the Placement property does not respect correctly.

If you have a modal Popup and update its PlacementTarget after IsModal is set, the Popup will not be shown correctly on Windows.

It would be nice to have more animation styles when the popup opens/closes.  Specifically, it would be nice to have an animation that slides in from a direction (top, bottom, right, left).  I would like to have a popup that appears to slide up from the bottom of the page when it opens and slides down when closing.  I know you can get a similar effect with the SideDrawer control but would prefer to use the popup.