I prefer Tomhet on the original album. It worked better as an outro to something great.
I agree. This is the weak spot for me, but it's not really weak to a new listener. I think Varg may have (unfortunately) listened to a critique of his original instrumentation from the peanut gallery. However, I liked the simplicity and 1980s innocence of the original, as well as its role as he stated it in the album: surging through all this chaotic metal, ending up in silence and death.
If anything newer Burzum ambient should be compared to some of his more atmospheric pieces from the second album, which sought to create a mood and then change it from within via texture. That's not entirely unlike what a lot of death metal did, except that now it exists through harmony and melody.
Some tracks, like the "ritual ambient" Heil Odhinn/Heil Freya originally struck me as really annoying. I recall these having been around for some time in concept, giving the feel of this album being odds 'n' ends. However, they work quite well in breaking up what otherwise would be an omnipresent sameness to the album.
The more I listen to it, the more it improves. The spirit and sensation is there. It has its flaws, but flaws don't dethrone greatness, merely give it some personality.