A good edtition to the Sim City Series, definately worth a look.
Another new feature which I thought was a great idea was to be able to add your own mp3s into the game itself, meaning you don't have to run a media player in the background, helping those with slower computers run the game more efficiently.
As for game play itself nothing much has changed since 3000, your main objective is still to build and manage a thriving city, though this time round you zoom out to the next level and have the chance to build and manage a thriving region. If you do so successfully you'll unlock a number of civic buildings, from farmers markets to convention centre's and military bases all which contribute to the city in which they are built in some way.
You can now directly alter the amount of funding going into each separate civic and utility building allowing you to only pay for what you need which is a big help, especially when your city is still young and may not need all the power a power station can pump out.
Overall Sim City 4: Deluxe Edition is a worthwhile game and an excellent addition to the Sim City Series. Even though in the way of game play not much has changed since the very beginning, but then again, who says it has to.