It depends...

I bought The Sims (and 3 expansions) and it was the greatest game ever for about a month. I was just consumed by the revolutionary gameplay. A month after that, it was still a great game. Then it really began to get repetitive. I bought Livin' Large, House Party, and Hot Date, and while these expansions added a bunch of new items as well as expanded gameplay options, the novelty like the Sims, wore off after awhile. Still, the game (and the expansions), kept me entertained for a good while. It was truly a great game.

The Sims 2 and the hype that surrounded it had be sold, and when I first started, I was amazed at the improved graphics and customization. But the game's novelty wore off really fast. I only played it for 2 weeks, before it got shelved. When my DVD-ROM drive died on me, the game (the only DVD-ROM game I have) was rendered unplayable, but it wasn't a big loss at all to me...

I guess these simulation games aren't really for me, I get tired of sending my character to the bathroom scores of times in a hour.

Still, Spore, from what I've seen, offers something new, but I never got into SimCity, and I burned out on The Sims, so I'm not going to get it when it comes out (Neverwinter Nights 2, Battlefield 2142, and Medieval 2: Total War will all be there). It may get consideration later if there is a lull in games that interest me, and I'll give it a go at it's reduced price...