I think the new campaign map was a good idea - but sadly the AI is intrinsically stupid and really struggles to get to grips with it. All too often it has little armies moving around with little to no cohesion, whilst other armies invade and slaughter the confused critters. With massively improved AI behaviour, I'd probably prefer the new map to the old system, but really it's a draw in its current state.

I'd have preferred to see a compremise until the AI coders have learnt how to improve the AI. Basically the provence/Risk based map, but with 3-4 mini-provences within each one. You'd still have lots more places to move than before (and lots more battlemaps), but it would be more linear and the AI would benefit greatly. Plus you could implement some kind of power-control system, whereby the more of these mini-areas in the provence you control, the more tax/trade and loyalty the current owner of the actual city would lose. You could therefore strangle the lifeline of the provence without having to lay siege to the city until much later. Sieges are so dire and poorly implemented that this would be a good thing in my opinion.

Another thing I'm not convinced about with the current map system is the battlemaps. They are generated and based on the landscape in the current square, giving thousands of individual maps to fight on. Sadly 99% are featureless, being nothing more than open ground with a few thickets of forest here and there, some hills etc, but seldom are the maps in any way interesting. MTW maps seemed to be a little more thought out, and typically the defender could scout for a good defensive position beforehand. The maps in RTW seldom have any natural defensive positions or chokepoints which ultimately makes battles very similiar.

In conclusion: new campaign map style was a nice idea, but needs improving or removing.