I'm not totally sure that I grasp how the battering ram and catapult work in this version. But, if they work how I think they do, then they need a boost in power.
First off..the battering ram. It reduces the city wall level by one. So, as I see it, a ram only reduces the actual fortifiction bonus half of the time. If it reduces wall level 7 to 6, or 5 to 4 then there is no effect? Am I understanding this correctly? Are the effects cumulative? Do two rams decrease the wall level by two? Is the effect permanent? Is the wall strength permanently reduced? If the effect isn't cumulative, and the decrease isn't permanent, then we are left with a 4 strength unit, with average speed and a pretty much useless ability that takes 2 turns to build. Why would I bother?
Lets move on to the catapult, it is guaranteed to shift combat strength by one during a siege. So, three turns for a slow, weak unit that is expensive to build and possessing an ability that is essentially a -1 during a siege? Am I missing someting here?
In warlords II the catapult negated fortifications. It was good sure, but is was slow to build, and slow to move.
In warlords III each point of siege reduced the fortification bonus by one. This worked pretty well, made siege an important part of the game, but not omnipresent or all-powerful.
Perhaps I don't understand how this siege system works. If this is the case, please enlighten me.