Once again, Joss Whedon shows what can be done with in a single episode of TV (okay, it went over by eight minutes, but life is imperfect).
By the time this show aired, nearly every sci-fi/fantasy series had tried a musical episode. This episode is an actual musical that fits in in the Buffy mythology and moves the story forward. Plus the songs can be taken as personal athems for the characters. Who doesn't think of Spike without thinking of 'Rest In Peace'? Of Tara without thinking of 'Under Your Spell'?
The singing was great by some, good by some, but you have to give kudoes to the entire cast for having the guts to try. My favorite singers were James, Tara, Anthony, Emma and Nick (their duet was funny and touching). I love Tara's song to Willow (cause I'm a hopeless romantic and it is an unabashed love song), Spike song and Giles song, especially when it segues to the duet with Amber.
And the acting is, as always superb. From Willow's reaction to Buffy's revelation, to the obvious pain Giles and Tara are feeling when they realize have to leave (my only complaint about the episode is that it's such a downer and the signal the entire group is going to fall apart).
Buffy's best ep? No, but definately one of the top five the series ever did.