Ive seen a lot of posts about the poor AI in RTW and im not experiancing it myself. The only bad play I have seen is the AI standing there defending while you pepper him with arrows.

I have had the AI lead one of my armies once and did a steller good job, I have also had it do a very BAD job too.

Playing against factions with fast light infantry the AI will always stop your flanking attempts. Now some people have mentioned how bad the AI is at protection its flanks and I guarentee you these people are referring to hoplite armies.
Barbarian armies with quick fast infantry I always have difficult getting around the AI's flank until the melee is well engaged.

The AI also likes to hit your flanks with cavalry, and draw out anti-cavalry troops with one unit of cav and charge your unprotected lines with another.

All in all the battle AI is about 10 times better than MTW, its just a few things such as the AI being ineffective with slow moving hoplites and letting you pepper it with arrows when its defending.

I lost probably about two battles against the AI in MTW on Hard in my entire campaign as the English. Most of the time if you were outnumered you were fine.
Ive lost far more in RTW and I actually fear being outnumbered now. Yeah the Gauls are easy , but try playing against some of the other more advanced factions and you will be surprized.