First of all, what FOAnatic said is true.
Second, your point is made moot by the fact that Sondheim didn't write the music for West Side Story. Regardless of your opinion of the show, why don't you compare it to a show where Schwartz has the same credits as Sondheim - as both lyricist and composer?
Again, for the record, I love most of Schwartz's stuff, so I'm NOT looking to put him down - there's no reason to put down the works of one to appreciate the works of the other.
That said, and I think the majority of informed theater fans agree, no one can touch Sondheim when it comes to lyrics and music. To say he lacks melody in his writing is simply ignorant.
Hi, Shirley Temple Pudding.