The AI is not horrible. I've read a couple of posts where folks were talking about its inability to adapt (set up good defense and it'll likely keep feeding troops and tanks in the meatgrinder). They may have a point. But then, I've never seen a wargame where the AI could really and truly adapt to what the human player was doing.
Up until CM, neither had I seen a wargame where a light tank controlled by the AI realizes it's in trouble, pops smoke, and reverses the hell out of dodge.
If a scenario is too easy as the Germans, or too easy as the Soviets, then switch sides. Odds are you were playing it from the wrong point of view in the first place. You'll sweat a little more trying to move your T-34s around an open field covered by King Tigers. And you won't like watching your crew brew up, either.
If that doesn't work, bump up the opposition's strength and experience.
But I just went off on a major tangent. The game is worth every penny. Go get it.