It does seem to be more or less as powerful as gold compounding is, depending on how much Stormlight you use.
It's a little more limited in quantity than gold compounding, since you can only hold so much at a time, but we've seen some people with Stormlight heal some pretty insane things.
It doesn't increase durability as far as we know but I do think it was also mentioned in tWoK that it increased strength, don't have books to hand right now though.