From what I have played so far of ruse, it seems like AA is underpowered, in a way of speaking. unless you have 3-5 AA units per plane, they can just have some planes take the hit and move right on to destroy your base/units.
I think AA should be made more powerful, or rather take a few less shots to kill a single plane. Right now it takes like 8 shots from basic AA. (IIRC)
I'm not sure if everyone feels the same, but from what little I've played it seems this way.