I thought that was great.
Some range of opinion here, but all about style. I think you nailed what you wanted to nail - a sort of dark, brooding, cinematic feel. You could do something very different with the song, but then it would be a different sort of a song.
By all means tweak, but my personal vote is for you to leave it with the same sort of style. It builds as it goes along so I think the dynamic of the song is fine. (Although I may be saying that because I did a similar thing with one of mine recently!)
That said, there are some good suggestions above and you could always try some of them and ditch them if they don't work. I remember trying that with a song - I had a vocal and nothing else, so built a song around that. I had this great idea for an odd strings part and spent ages doing it all and... it sounded awful. Trial and error is a great recording technique
I went to bed singing the hook after listening to this song - always a good sign.
BTW - can you do a summary of what you did with the main vocal in terms of processing? I thought it sounded good.