Persian Hoplites: are the result of Achaemenid attempts at incorporating various aspects of Greek warfare in their own military.
Due to various reasons the Persian Hoplites ended up as:
1) A light version of the post-Peloponesian War hoplites.
2) Lacking the spirit and superior discipline of their Greek counterparts.
3) A mix of Persian and Greek influences.

They were very disciplined compared to most other Persian/Armenian infantry; but were still no match for properly organized Western infantry. They are reliable infantry, nonetheless, and can provide your army with a key element in siege/assaults; and are always good for added punch. You should however not try to rely on them as a substitute for heavy infantry when you play as Armenia or Parthia - your best bet remains the archery with a core of heavy cavalry.