The intriguing possibilities means Sims 3 is one of the most playable games you'll likely own on your computer -- if creating neighborhoods and watching virtual soap operas are the sort of things that interest you. The main drawback, of course, is the omission of key features found in the Sims 2 expansions over the years. You can have day and night cycles, but not seasons or weather. You can have a fish, but not a dog, cat, or bird. You can go to the library, but not attend a university. See a trend?
This content will certainly be reintroduced over time, for a price, through either the Sims store or as part of separate expansions. If you can live with this, and aren't expecting a completely different take on the series, then Sims 3 is money well spent. It's sunny, silly, and sweet. It's just not quite everything it could have been.