So I did some 1 on 1 test in custom battles. Pikemen is the **** in this game in the phalanx formation. Beat sword, calvary, elephants, other shorter spear units. Weak against skirmish missles, and not so good in sieges when climbing up to fight at walls. And not so good in auto resolve. But in open battle, unbeatable. Royal spartan lost to Spartan pikemen 1 on 1. Best of all they're cheaper...at half price.
My royal spartan couldn't beat very heavy melee sword units 1 on 1, but pikemen crush everything, they switch to sword in close combat (unlike regular spearmen), and the men behind them stab enemies with pike. They can turn direction quick too.
Other shorter spearmen seems to break phalanx formation when you order them to attack. When close to enemies, they just charge and lost formation.
Despite, being strong somehow enemies can break through their phalanx rank easily though. Just double clicking behind them will break their ranks render their formation useless.