If it's the same as the kind we have in Kansas the only good I know of is to make more work for me to eradicate it from the property.
Seriously, though, I have heard of it being used to make gun stocks. Supposed to be quite beautiful. And it makes excellent fire wood. Puts off a lot of heat. The longest thorns I have seen were close to six inches but I have seen some thornless trees on the property. They spread by seed and by runners from the tree. Runners travel quite far until another tree pops out of the ground. One tree can very soon have a dense stand around it. It survives our winters quite nicely--zone 5/6. Goats and sheep will eat small trees and leaves they can reach and it seems to draw bees in the early summer. Don't know about the nitrogen fixing. My main complaint with them is the sharp thorn and spreading into areas I don't want them. Please donate my seedling--if earned--to the charity of your choice. As long as it's far from here.