In all of these types of games, the enjoyment one gets out of the AI depends hugely on your expectations and your conception of what an artificial opponent is supposed to be. As a veteran of Grigsby games dating back to the early 1980s, across multiple platforms, I've always managed to enjoy the games solo even when (as was usually the case) an objective measure of the AI's tactical or strategic abilities would find them wanting. Maybe it's because I (mis)spent my youth playing board wargames solitaire, given the difficulty in finding reliable opponents, but I approach most historical computer wargames with a sort of solo player's mentality. It's the process, not the result, that matters.
So I don't go in thinking that the AI has to be a veritable Manstein or Zhukov; I'd settle for simply presenting me with a framework within which bad decisions on my part get punished and good ones are rewarded. I'm not concerned if I actually win all the time; I'm not looking for a purely competitive challenge in that regard. Rather, I'm looking for a structure within which to "play out" historical campaigns in a fashion that is intellectually satisfying. I therefore tend to refrain from using every nuance of the rules to crush the AI, but limit myself instead to things that I feel are more historically accurate or relevant. Should the AI be good enough to make such circumlocutions unnecessary? In a perfect world, sure. Should the AI be able to deliver a tense battle, with the outcome in doubt? Definitely, if we could write the script for the game industry. But I don't really use those desires as the bar for my expectations. As long as the AI doesn't do something really abysmal--routinely move every unit to the upper-left corner and pile them all into one hex, or something--I'm usually ok, in games with as much historical detail and "chrome" as this one. The simpler the game, the more apparent the AI quirks are, but the opposite is true as well. A very complex game can hide weaknesses in AI behind detailed systems, and often this helps make the experience more palatable.
None of that helps if your primary interest though is competitive play, naturally.