One of the biggest complaints in the reviews, and often echoed on the various forums is the AI is too easy. Very hard to balance across all the ability levels for the poor guys trying to. Perhaps more AI levels would be the key, if more people felt like this with penalties to the AI beyond beginner, and bonuses above godlike?
BTW Too easy to me also means, we've played more hours or are more used to the way the game plays, so the average player is generally better at this type of game.