It was just approved by GM and I think you will be hearing more about it as time goes on. I have heard that it helps keep moisture out of the seems also, reducing the chance for rust. I have seen a few jobs done with glue, they look nice but I can't say how strong it is.
I am new to body work but not metal, I have used panel weld epoxy sold at finish masters on Box Truck tears on Rental trucks to repair tears in the box , nothing works better for that, Also seen used on car panels and havent heard any complaints, has flex to it and I used to fix my old plastic bass boat and its leak free, just doesnt have enough beer holders tho ::
The glue that they have developed is some amazing stuff, but i don't think it is right for our mustangs. the flanges are all small (big enough for a spot weld) and the panels require alot of bending and twisting to get them on the car right; ie, you have to weld part of it on, bend it, weld another part, etc. i think you would be better off welding the mustang panels together. leave the glue on stuff for autos that were designed to use glue on panels.
just my $.02
When I though I was going to do the body work on my fastback myself, I glued on the taillight panel and the quarter. It is really easy to use and looks like it works. But I gave up on the car and it has not seen the road. Don't know how it would hold up.
The only drawback I have heard (but not actually seen) is that if you flange a quarter skin and glue the full length the seam will show through the paint after about 6 or 7 months. Again, I've not seen it but a body man told me about it... It doesn't necessarily mean he did the job right to begin with...