It's great - the graphics, the new music, the online Store interface (and the free points to spend in the store!) along with the ability to customize via color and pattern almost any item, but there is a bit of a learning curve for veteran Simmers.
Much of Build Mode and Buy Mode are the same, although there are a few items from previous versions that are absent, and overall game play remains familiar, but there are some aspects of the "new" features that I personally don't care for.
Those familiar with The Sims, and Sims2 (and associated Expansion Packs and Stuff Packs) will be able to quickly jump in and get going; those new to the franchise will want to proceed a little slower, and follow the Tutorial tips as presented. Just remember that each "household" that you play is a "saved game", but unlike in previous versions, Sims all over your town will continue on with their "lives", aging, marrying, changing jobs, and having all sorts of adventures, even when you aren't controlling them directly. If you want "total control" of your Sims life, then you will only want to play one household per town.
MAKE SURE YOUR COMPUTER CAN HANDLE THIS GAME PRIOR TO PURCHASING! Many of the problems that new users have with this game can be traced to trying to play the game on equipment that can't handle the intense graphics requirements of the game.
Overall, I'm glad I got it - I just need to get used to the new game play! :)