The songs themselves are fine, as they ever were. Listening to them with this "good production" (relatively speaking) casts a small amount of new light on them, in some ways. The vocals ruin it on every track but Black Spell of Destruction, where they're only just "not awful". My Journey to the Stars and parts of Key to the Gate sound hideously rushed, which is a crying shame. Digital recording makes the whole thing sound thin and flat, and the "polished" nature of the release negates the character that these songs had in their original forms.
Vikernes needs to compose an album's worth of material in the style of all of these "introductions", which are the most atmospheric thing about this release. I seem to remember that the Intro and Outro of Fallen were the most interesting parts of the entire album (i.e. they were actually interesting), too. Fill two sides with an epic each.
Despite the generally low quality of this release (3/5, maybe), I've found it to be worthwhile. I know I'm not going to listen to these new versions more than about once a year, perhaps, but I also know that I'm never going to hear the old versions the same way, and not in a bad way, fortunately enough - it's like the songs themselves have been slightly "expanded" (I can't quite put it into words) by being presented in this different setting.
I think this might have inspired me to write Black Metal again. Oh dear.