When you spray it on the wall, starting at the bottom, everything will seem fine. But when the pile of foam starts to build up, it's probably going to collapse and you'll have a huge mess.
I suggest using something like Foam It Green (www.foamitgreen.com
). That's what I used and it was great. There are other companies that sell similar setups too, so shop around.
I hadn't ever used anything but Great Stuff foam for small jobs, but I needed a lot of it because there was a large area to cover. It would have cost much more to buy enough cans of G.S. to do the same job the two 60 lb. tanks of F.I.G. did. If you have a smaller area to cover, they sell smaller tanks too.