It brings new humour, new methods of interaction, and a much more fleshed-out portrayal of personality for your Sims. In fact, it can be argued that this is the desert-island expansion pack; the pack you'd choose if you could only pick one. If you own the Sims 3 you need to buy Generations.
With decent graphics, great sound effects and good old fashioned Sim gameplay with lots of new content, The Sims 3 just keeps getting better and better. Recommended to all lovers of the Sims!
On its own Generations isn't going to do much for your experience, but in conjunction with everything else it just makes for a more interesting experience.
The sims' social life finally get the overhaul they've been longing for. There no new burrough or new main feature, but there's plenty of golden nuggets strewn about in every corner of the game, all of which are well worth looking for.