Actually, the Iron mode is much more easy than "basic training".
Speaking about making new players stay in the game, I would recommend to do something with basic training skill level. I started playing on it and only my persistence and geniune love for war (I'm a pacifist) made me continue playing.
On basic training AI gives real hell with 2 minutes wait time for artillery. It's like constantly being lased from drone and suffer from innumerable artillery shells. Frankly, it's no fun.
Playing on Iron after that feels like the breath of fresh air.
And I'm far from having inflated sense of my skill level. I know for sure that I suck at this game