I'm not used enough to Dom2 (wasn't even that used to Dom1 ..), but I think the main gameplay change comes from the reduced gold income, itself coming from the new tax/no patrol system.
I fear that Dom2 games will be rather "smallish" in terms of army size compared to Dom1, so focusing more on elite troops/SC (as many pointed out).
But conversely note that the reduced mm will allow us to play larger maps, thus giving nations more gold/resources...
So we've still to experiment, but surely we have to adapt - and changes are always unwelcome to old vets
