If you are considering the "Collectable" series, this double disc set comes highly recommended. There are some fine reviews on here, so rather than repeat anything that has already been well stated, I will instead give my personal account of having first heard the Paris material.
It was sometime in the very early 80's, and before I had even heard the Discipline album, a buddy of mine came up with a copy of what is represented on the material from the Paris show. Yes, the sound quality was not great, but the mind-boggling music caused you to not even notice most of the time. They were calling the band "Discipline" at that time, and there were liner notes about "beating the bootleggers".
Years later I asked about it hoping to tape it (no CD recording yet), and was informed it had been misplaced.
I recall at some point that I searched the internet for a copy & decided it was so rare the best one could hope for was to stumble across a vinyl copy while trolling throgh used record bins.
I recently decided to check for it on Amazon, just for grins. Initially I didn't have any sucess, until I started looking at the "Collectable" series and was amazed to see it as a part of this 2-disc set. I was a bit sceptical that it was the same performance, but as soon as I heard it I knew for sure.
I don't know if anything was done to improve the sound, but let's face it, there's only so much you can do with a primitive live recording. However, as before, listening to the energy & brilliance of the performance caused the lack of fidelty to become almost unnoticeable.
The energy is amazing as this group of accomplished musicians run through what was to them at the time relatively new pieces of music and with apparently limited rehearsal. This was also a rather new style of music they were attempting to create (they didn't even adopt the King Crimson name until later). The challenging songs are performed with gusto, and perhaps the fact that it wasn't the hundredth time they had played them yet added to the many facets in evidence on these particular performances.
The Philadelphia show is great also, with more tracks and better sound quality.
I can safely say that with a few exceptions I would still prefer the fresh raw energy which was so pervaded the earlier Paris performance. The fact that it was a tiny room in a small club brought a certain dynamic as well.
In closing, if you enjoy the early Belew-era KC, you should definetly consider this one.