I'm curious what the best use of the Hoplite/Companion combination will be. If a Greek player beelines Bronze Working, then does the same for Horseback Riding, they'll have a lot of time to build up veteran Hoplites while waiting on Companions to get researched/built. I'd guess that ancient Greek armies will be mostly Hoplites with Companion as support; possibly, a small number (<5) Companion will rush ahead to disrupt defensive formations while the main Hoplite line marches up, or the two stay together until engaging the enemy, where the Hoplites hold the line and the Companion flanks.
Seems like a very powerful one-two for the Greek player, and something I'd rather not be on the receiving end on.
5 speed.
Companions move faster than Modern Armor, almost as fast as Gunships.
That and a seriously beefed up Spearmen is a nasty, nasty combo. Even when you hit the iron age it'll be nasty. You can build less swords because you have stronger spears, which leaves you more iron for catapults.
In fact, Companions are actually somewhat comparable to Knights. The strength difference between Companions->Knights is the same as between Spears->Hoplites... and Knights only move 3 instead of 5.