It's a big box so i'll do this by section, cos i haven't listened to them all yet, and i firmly believe in giving any new album several listens before passing on my impressions of it.
I started with the 70s Shakti discs, because they were a great, great group. An inspired marriage of the Indian and Jazz improvising traditions.
First up, here's a link to a pretty good review of the box;
http://www.allaboutjazz.com/php/news.php?id=2997
IMHO the Shakti performances on here are beyond well worth having. Particularly because of their rarity - there's been a few boots around, but generally of lamentably poor quality. The level of musicianship is stratospheric as one would expect, but Shankar tends to hit the high notes a bit too quickly - he should be pacing himself and giving his solos the narrative flow they have on the studio albums.
The percussion section is a dream team and Zakir in particular plays a monstrous solo in Get Down and Sruti (disc 5). There's an unbelievably fast bol duet in Nata (disc 4).
Minor Quibbles;
As always, with a live album you don't tend to get that through composed feeling i.e. with a sense of structure and dynamics that are clearly thought out. Any live albums that get released tend to have this, because they are cherry picked for it. (think of Agartha and Pangaea, and compare them to any boots from other gigs on that Japanese tour).
Also a relevant comparison - the first Shakti album, recorded live. I really missed some of the high points on that album, which just don't occur on the performances here. I'm thinking particularly of when John hits a chordal riff that just peaks the song.
I couldn't reccomend this music more, although the original albums are still the first place to go.
Next up: Mahivishnu Orchestra Mk III (I think, anyway it's discs 1 & 2)