Be under no illusions - this is an unofficial CD. It's a radio broadcast of their legendary Tribal Gathering performance. The front cover betrays the bootleg nature as the picture isn't from the gig, it's a more up-to-date photo- the Kraftwerk consoles and even one band member have changed!
It's not the whole set but features more tracks than other bootlegs I've heard from the gig (I wasn't there personally.) Sound quality is fine but audience chatter features heavily in parts. It includes the unreleased track they performed and captures the excitement of the gig which was a big deal at the time.
With this and the Soest CD that's also out I half expect Kraftwerk's lawyers to be on the case so if you're interested I'd buy this quick but only if you're a Kraftwerk obsessive/completist (aren't we all?).