I find the upgrade path to be worth it if I'm playing a militant game. If I can recall, iron working is along the way to metal casting or whatever tech gives you the +2 production building, which is a significant boon if you're going militant. Add to that that the swordsmen upgrade path is one that lasts all game with the same type of quite powerful units that are useful in every single era. When those heavily upgraded pikes turn into lancers, all of the sudden you're either training new front line units or are adopting an unorthodox style for attacking cities.
I don't think they need a buff. Simply because they aren't the obvious choice every time and there is another viable option to leading with swords that has distinct advantages in itself doesn't make them underpowered. The path Iron Working is on is not without its charms, and swordsmen upgrade to muskets/rifles/great war infantry unlike spears, and keep the upgrades they have from their very first unit. Elite front line units are to be treasured, and if you did happen to invest in the honour tree early on and kept going to war, by the time you're hitting infantry you will likely have some utterly amazing units spearheading your army. If you went for spears, you essentially lose the entire early period as a time for training your front line troops, since spears turn into cavalry type units after pikes.
Edit: One thing I'd like though.. Reveal iron with bronze working. Make going swords less of a gamble.