Definitely a 'he' in English. The same goes for all the Ainur we have met so far: Melkor. Manwe, and Ulmo.
(The Silm is, in general, extremely male-centric. Of course, it's supposed to be a book put together by loremasters, so one can always just blame it on them...)
Things I enjoy about this chapter:
-- It is a foretelling of everything that will happen. it also highlights the importance of music in this universe.
-- The whole 'creative struggle' bit at the beginning makes me (as a creator) feel some sympathy for Melkor. Sure, he's a bit of a diva, but he's the only one trying to be Creative on a large scale, and I have to give him props for that. (Also the whole music-battle, with the different pieces described, is a little 'Devil went down to Georgia', but with the person opposing the Devil being all-powerful, which makes much less fair.)