The Sims 3: World Adventures is an experience that deserves the title "expansion." It adds a lot to the core experience of the game, it offers an alternative style of gameplay and it's pulled off in a way that blends pretty well with the game (with the exception of the hiccups mentioned above).
If you're a Sims fan, though, you've probably already guessed this having played the game for the last month solid. But if you're not really a Sims fan, or you were one of the skeptics who were holding back because the rampant expansions of the Sims 2 tired you out, don't hold back. There's a whole wide world out there for your Sim to explore (three of them, in fact) and you won't want to miss it.