Phalanx units are great (providing of course you don't get flanked).

Last night upon completion of my short Julii campaign, I decided to go for a Greek Cities Campaign... Man it is tough. Besieged right from the word go on Sicily first by Carthage and then By the Scipii.

Taking Corinth from Macedon was a true pleasure and demonstrated to me the true value of the Phalanx as they marched down the narrow streets and mowed down all in their path... It took a very long time to capture the place

You have to be very careful with their use, and always remember to remove them from the Phalanx to be able to move quickly.