I'm not a fan of this, just because I'm against the idea of having a set liturgy for any type of marriage.
But you nevertheless I hope understand the purpose of such in the Episcopal Church, which views marriage as a sacrament? This isn't technically the marriage sacrament itself but it's a way to raise a civil marriage to the level of a sacrament.I wouldn't support having a set liturgy for baptism or communion either, the only things in my type of tradition that would considered sacraments (though "ordinance" is the word more likely to be used), nor is there one (unless the Trinitarian formula counts, but even what the baptizing pastor asks the baptized before dunking them is basically up to them to word in whatever way they want.)
Oh and thus it can't be used in states that don't recognize same sex civil marriages? Then it's kind of discriminatory.
(Granted, I agree with you on the subject of this particular liturgy not being particularly well-written, but the House of Bishops amended it to make it a lot better than it was initially. The House of Deputies legal wrangling was a nailbiter but of course turned out to be bullsh**t in the end.)
I haven't read it, but I view having any set liturgy for this type of thing as equivalent to having some type of liturgy at a show instead of just letting the bands say whatever they want. To use a fairly crude analogy. I'm not even a fan of having the bands having designated start times! (Though I understand how it is often necessary.)