One of the major redeeming qualities of Animal Crossing are the collectible NES games, which look like NES systems with an NES game box sitting atop them. You can use them and play them through the Gamecube or use Advance Play and load that game into your Gameboy Advance/SP's temporary memory and play it on there. But the systems are pretty hard to find without using cheats.
Like many games that have no true ending, must like Harvest Moon, Animal Crossing gets boring and monotonous after a while. You can only talk to everyone in town so many times, you can only wait to receive the last fossil you need for the museum so long and you can only shake so many trees hoping to get money and not stung by bees.
But there are collections such as bugs, items for the museum and other things that keep the game interesting. The town changes with seasons, there are random visitors who will stroll through your town on occasion and there are town events on real holidays, tracked by the Gamecube's internal clock. But the hype of events and the fact that the game coincides with real life really tends to ware off after a short while.
I haven't played any of the sequels, even though I want to, but I imagine they were built off of what Nintendo learned from the first one here. The game hit with a huge bang, as it was almost all I read about when it first came out and I was eager to give it a shot. The buzz lasted for quite a while and it seems everyone who owned it really loved it longer than I could seem to muster, thats not to say I don't love the game, but I've simply let the novelty wear off with newer games having more replay value than taking the time to visit the poor folks who inhabit my Animal Crossing town of Hell.