I am someone with prior exposure to a lot of the Matsumoto-verse, including several of the older Harlock series/movies. And I really enjoyed this one!
It's in a completely new continuity (surprise!) and some of the characters have changed. But in my opinion it worked really well. And it's not just stunningly beautiful, but also succeeds to embed you in the atmosphere of it all. To suck you right into that world.
And it comes with a big twist (twofold even), that is well executed.
A few minus points here and there, where I felt that something didn't work out well or felt somewhat rushed. And yes, some things won't make sense if you think too hard about them. But it's definitely worth the watch and at least for most people buying the DVD/Blueray. I got it within hours of first seeing the movie at a convention.