Hello, I'm currently playing the full historical campaign as Western Entente against the AI. I use the 1-03 version of the game.
I have some observations to do.
The AI seems able to form fronts and seems more dangerous than in the game España 36.
It seems to use well balanced forces against me.
It seems to make good diplomatical décisions and also good economic décisions (raising money...).
But it doesn't seem using/buiding any airfighters. My rec air units have only once (august 1914-july 1917) met enemy airfighters (in the Balkans). I have destroyed easily a big number of german rec aircrafts (in 1915, 1916 and 1917), because they were unprotected.
The AI has not used the Zeppelins card (apparently).
The AI has not used gas attacks (apparently).
When the AI does retreat to defend a new line, it lets some small supply units to garrison the towns. These supply units are rather easy to capture.
I believe that if you could correct these behaviours, the player would have really a harder time : he would have to build replacements for his aircrafts, to buy more airfighters. The british morale could be lower. He could not capture easily some support units.
It's not a critic of the AI that seems rather good. I have tried to find its weaknesses.