Buffy is clearly written by a less experienced Joss than Firefly, but the same kind of fun is present in the dialog of both. Buffy is less consistent in quality than Angel, but at times much better (and at times much worse). The musical episode compares well to Dr. Horrible, although the latter was again, clearly the result of more experience.
It's well worth seeing, and season 2 and 3 compare favorably against anything else Joss has done. Season 1 is a bit on the cheesy side----but once you accept that, it's not the bad kind of cheesy. Season 4 weakens a bit, but season 5 recovers nicely. Season 6 and 7 are a bit weaker but both have moments of brilliance.
Now, most people will say that Buffy herself is one of the less interesting characters on Buffy the Vampire Slayer
. But it's an ensemble show, so that's okay.
I recently found some fan-made Buffy and Angel trailers on Youtube which are really *very* well-done....
Angel Season 1
Angel Season 2
Buffy season 1
Buffy season 2
Buffy season 3
Buffy season 4
Buffy season 5