So, first things first, I'm not a massive Joss Whedon fan or anything. I saw a small handful of Buffy and Angel episodes many years ago and thought they were self-consciously cute and juvenile, so I never bothered. Then, I watched the movie Serenity, and liked it very much.
So now my wife and I are just finishing off the DVD of the series Firefly - and man, is it good. I mean, Deep Space Nine good. The characters are instantly loveable, the tone is great, the scripts are tight...I mean, it's really, really good science fiction.
So....Dollhouse. I've heard nothing about it. We're looking for a new sf series to rent. Is this one very good, or is it not worth the time?
I can't talk about Dollhouse as I haven't seen it yet except for the first couple of episodes, but man oh man are you making a mistake if you don't give
Buffy and
Angel a chance just based on a 'handful of episodes'. You might have seen the wrong episodes, but trust me those series are a lot more than "cute and juvenile", actually
Buffy stops being juvenile after the first one and half seasons and is increasingly less so with later seasons,
Angel is rarely 'juvenile', and as for cute... There's always, or almost always, wittiness and humor, but there's a lot of great drama and darkness. But these aren't shows where you watch some episodes and skip others, even when the episodes are 'standalone', so much is about characters and their development and relationships. You just have to keep in mind that
Buffy season 1 is much weaker than the rest of the show, and is indeed 'cute and juvenile', but it gets much better later since the second part of season 2, the show is on the whole other level.
Angel season 1 is also not on the level of the rest of the show, except for a few episodes - it has too many standalones and is pretty straightforward, while season 2 has a great arc and is darker and has a lot of moral ambiguity, and the same goes for the next seasons.