One of the things I love about Season 1, having just completed a year-long rewatch of the entire run of the show, is how many themes are raised in it that Whedon gets to revisit in more detail, with twists, later on. It's marvelous.

And season 1 is... cute. Fluffy. Everyone's young and perky, even Giles, although their wardrobes mostly improve over the course of the series (there are great cheers when Giles finally ditches the tweed).