Though it takes some getting used to, SC4 RH is deffinitley something that you can enjoy to some kind of extent.
Rush hour is an expansion pack, but it offers more things for you to use than what you got in SC4. It includes El trains and ground highways, but also many features that make it extremley useful in building a city, such as making a smooth transistion from roads to avenues to highways.
It's pretty much the same thing, except there's a new Euro building set, but there are hardly any gimmick like features that found in SC3K unlimited. The music of the game has somewhat lost its jazzy feel and is replaced with wierd sounding forms of modern styles. Thankfully, you can add your own MP3 format songs in the library.
There isn't much to expect but a mere useful of features, but it deffinetly comes in handy.