I would agree with you. What makes it so hard is the command point system or whatever they call it that allows you to build only a few units while the opposition has 2 or 3 crawlers and so many units all over the map. You can never seem to build up a large enough force to accomplish your mission.
It really is a poor play mechanic in that it does not encourage you to conserve your units, but to just send them into battle as fast as possible and get them killed (along with as many enemies as possible), so you can build more units.
I finished the first few missions on normal, but am considering switching to "easy" to just get the game overwith and see what happens to Kane. It certainly is not very fun gameplay.
BTW, to me the voice acting also seems much inferior to the earlier games.