People have said that, considering people's behaviour to The Sims and Sim City series, it might get old fastish, despite the infinite possibilities.
But here's the way I see it:
You spend 50+ bucks to spend a day at disneyland (I've never been to the US so I don't know the price, but it's a guess based on some of the good theme parks here in Australia). So if you buy this game and it lasts you a week, you got your money's worth!
I don't believe this compares well to the sims/sim city games well at all to be honest. The problem with both of them is, for me atleast, that you spend all your time doing nothing at all. You'll spend 5 horus or so building up a massive city or poking your sims about and somewhere along the way you realise that your not actually having fun, you wonder why your not having fun, surely you must be having fun, everyone else is having fun, maybe the fun is coming soon, maybe it's not, maybe this is all there is too it... maybe your doing something wrong, maybe your meant to be achieving something else instead at this stage you should stop... but you probably don't. I've always thought the objective of those games was to "have fun" and personally i never completed them.
Maybe if you can get a decent income from your sims job, get him some happy relationships or so, maybe make your city profitable some prize or brilliant event will occur. Some reward for the work you put in but no.... there is nothing. In fairness these games aren't really games, the clue is in the title, they are simulations really just kinda quirky ones. Lets face it the only real fun you get is when you doing stuff your not really meant to. Killing your sims or rolling in tornadoes and floods or so.
Spore is different though, from the get go your hand crafting stuff. This isn't pre made building models/sprites or slightly adjustable player models. Though there might not be a true game completion section, messing about creating new creatures and throwing them up against others will be loads more entertaining than the sims games or so. In truth I consider Spore to be completely different, for spore is a game, whilst the sims games and their varients are, as far as i'm concerned simulations.
(especially the last "The Sims" game that had little to no cusomisation.)
I reckon the customising of creatures/building/vehicles will keep people playing Spore for a long while and even if it doesn't it won't matter, it's not like a proper mmorpg where you need player filled servers.
