Terrains are ugly as hell and obnoxious to build with. Sure classics like bedroom and slopes will be missed, (though there is a load of the bedroom made out of bricks) but this is a building game where you have to get off your lazy ass and build yourself some fun.
Plus, the lovey new graphics make up for the loss of those ugly old terrains. (though I will probably miss that one map that was like flying around a house)