Angel is a difficult show to sell to those who aren't already sold by the mere mention of Joss Whedon's name, because it is much more than the vampire detective show it first purports to be. By the series finale, all of Angel's characters have borne such loss and grief that some are almost unrecognisable, and they are prepared to die fighting an army of demons. It's a far cry from the show which once marketed itself as the adventures of Buffy's brooding ex-boyfriend in Los Angeles. While Buffy remained relatively accessible even in its later years, Angel explored complex aspects of its mythology like pocket universes without pausing to reiterate basic information to the audience. As far as vampires go, it eventually ended up with both Angel and fan favourite Spike, and it wasn't afraid to poke fun at Angel's melodramatic backstory. As Angel grumbles in parent show Buffy the Vampire Slayer's final episode, "I started it, the whole having a soul, before it was the cool new thing." Arguably, Nick Knight beat Angel to it, but the show alternates between dark and upbeat so well that it's in a class of its own.
