I did the first 5 scenarios and only won 2 on first try (iron). But each were epic fights ! Finished "Brutal" scenario yesterday and it was for me maybe the best defensive scen I've played in CM.
There's one thing that would help the AI a lot I think (if possible). It would be the use by AI of "blind" supressive fire on key areas.
For exemple, in brutal scenario, I had mid game at least 10 russian vehicles overwatching the town for more than 5 minutes. But none of them fired a single round while overwatching and then died when they entered the town (ambushed by my hidden RPG teams). If those vehicles had supressed (blindly) most of the buildings they could see from their overwatch positions it would have been a lot harder for me.
I'll try this idea in the scen editor and report if this work well.
Anyway, AI is better than most other similar games !