I thought it would be too child like when I was looking at the box, but to be honest its a nice change. You feel like a kid again. The graphics aren't revolutionary but the engine seems so simple and yet lets you do so much. When you build stores and zoom on them, your player name is on the sign outside. Little things like that which make the game more enjoyable.
Sound is like what everyone else has said.
As others have said also, it does change based on the year. Once I hit 1960, it changed instantly and was pretty cool. Nothing fancy, but its nothing bad either. You'll enjoy it. In Monopoly Tycoon, from the creator of Rollercoaster Tycoon, you design a city.