This is extremely boring to watch, and all that happens is we discover that Phoebe can't go to Ross's wedding, and Rachel doesn't want to go, and Emily doesn't want to invite her, but Ross is okay with it.
The reason this is so much worse than the other clip shows is that the other clip shows have more episodes to select clips from, and they focus on trying to be funny, rather than trying to sum up a relationship. The One With The Vows would be one of the funniest episodes that you could show someone new to Friends, but this isn't very funny at all.
Some good points about this episode is that it does sum up Ross and Rachel's relationship well, and is good for people who have only watched the 4th season of Friends, not to mention that it must be truly fascinating to go back in time and see clips from earlier episodes. It also increased the money they could spend in the season finale I suppose (although they were already given extra money by channel 4).
This episode can be a bit of a tearjerker too, especially with the scene from The One With The Prom Video, so that gives this episode a little extra credit too.