What can you all tell me about Muramatsu flutes? I have heard that they are endorsed by James Galway.

Many top professionals play them. They are outstanding flutes.

James Galway plays them, and claims they are not especially made for him. He claims he is not paid to endorse them, nor gets them free or anything.
In 2003 he claimed that he uses their cheapest model - bought off the shelf - for his practice, and regards it as a great flute. I too, have found this particular model to impress me more than most other-make, professional flutes, even gold ones.

Muramatsu make a choice of about 10 head designs - that is DESIGN (the IMPORTANT parameter), and quite apart from making parts of the heads from different metals, which is relatively unimportant but which so many players seem to focus on). People who negatively judge Muramatsus were more than likely playing on a head design that they were not used to, or which does not suit them..