I continually see two huge problems with armor in 0.34.11. The first is caps. Toady changed caps to be "shaped", which means they cannot coexist with a helm (which is also shaped). All your immigrants show up with caps on their heads, and this prevents them from wearing helms. Even if you never produce a cap yourself, and pray for all the imported caps to disintegrate to nothing, the invading goblins might still bring more. The workaround for the cap issue is to change your soldiers' uniform designation from over clothing to replace clothing. With that setting, soldiers will strip their civilian attire before beginning the Pickup Equipment process. However, this workaround also means that your soldiers won't have any clothing on until they get armored -- and if you don't have, say, enough greaves for everyone, then your soldiers will get very bad thoughts from their exposure. You may wish to throw in some clothing along with your armor in your uniforms, both to avoid these thoughts just in case you ran out of greaves, mail shirts, or whatever, and also for some slight additional padding.
(If you wanted to armor up your civilians by putting them all into inactive squads and assigning them minimal uniforms with a helm, shield and crossbow -- which used to work great in 0.31 -- then you'll run into the same problem now. Armored civilians would also need to replace clothing, so you'd need to assign a whole bunch of clothing to the uniform.)
The second huge problem with armor in 0.34.11 is boots. It seems damned near impossible for a dwarf to figure out that he has two feet and therefore needs two boots. A race that can engineer airtight doors and remote wirelessly-controlled mechanisms out of rocks but can't count to two boots... by Armok, it's a dwarf! In any case, virtually all my soldiers run around with two socks and one boot, despite piles of steel high boots sitting in the armor stockpile and in the forge. Assigning two pairs of high boots in your uniform seems to be the only workaround for this one.