P>I picked up the first cd release of this back in either the late 1980's or early 90's (somewhere around there..!), and found it to be a very satisfying visual experience. I lost that copy (at the second-hand shop where I sold it..) and had recently desired to have it again for my archives!
This beautiful edition, made up of both the "Primary Phase" and "Secondary Phase" episodes, includes 2 additional discs of 'special features'.
Disc 1 is the VERY listenable "Guide to the Hitchhikers Guide" containing interviews with the author Douglas Adams, 3 members of the original radio cast and those who had a hand in bringing the Guide from concept to product. It is narrated/hosted by Peter Jones in a cleverly scripted psuedo-reprisal of his role as the book in the radio series!
Disc 2 contains a more formal interview with Douglas Adams, which we can only imagine was recorded around 1998 when the "Guide to the Hitchhikers Guide" was produced.
The sound quality is pristine and flawless, it doesn't appear to have been remastered in any way from the first cd release (the copy I owned I mean!), simply because it didn't require any technical upgrading. All 8 cd's are individually packaged in illustrated cardboard 'sleeves', with a total running time of 7 hours 40 minutes. The recording is in stereo.
Totally worth your money if you are browsing for an 'ultimate edition' of the first Hitchhikers Guide to the Galaxy BBC Production :D