I'm having some issues figuring out how to actually add slides from a NextGen Gallery (an excellent idea to support it by the way). Once I select a gallery from which to ad slides I'm not sure where to go from there. The "Use as featured image" link is a mystery and when I click on the "Insert Into Post" button it simply takes me to a blank page that never does anything. Whether that is an issue of my browser or the plugin I do not know. Some kind of tutorial for this part of the plugin may be helpful.
Also, I'm not sure how the NextGen gallery support is supposed to work at this point but if you could add support for adding images from an Album that would be awesome. One of my biggest issues with NextGen is that it cannot do a slideshow for an album; only galleries and the ability to do so would be very helpful for both myself and my clients.