I don't normally bother buying compilations, other than of obscure psych from the vaults (that all started with the original "Nuggets" double vinyl album, by strange coincidence itself on the Elektra label). This is probably as near as any other compilations come - plenty of obscurities and quite a bit of psych. The fact that Electra was one of my all-time favourite labels and the sheer magnitude of music on it clinched it. Be prepared for lots of folky stuff from the earlier years, however.
Discounting the earliest folky/jug band stuff, well known material includes The Doors, Nico, Love, Judy Collins, Butterfield Blues Band, Tim Buckley, The Incredible String Band, Delaney & Bonnie, The Stooges, Bread, MC5 and Queen. Commercial but less well known material (to the masses at least) includes Eclection, Mickey Newbury, Rhinoceros, Jobriath, David Blue, Plainsong, Fred Neil and Clear Light. Obscure stuff, except to those in the know, includes Crabby Appleton, Leviathan, Dino Valente, Stalk-Forrest Group and David Ackles.
Add fold-out hardback CD digi-packs including photos of singles in their sleeves, 4 full-size album cover photos, badges, memorabilia odds and ends, a superb hardback book giving much detail about the various songs and artists from contemporary comment etc and a DVD-ROM of the excellent book about Electra Records "Follow The Music" plus a discography and you have an unsurpassed package especially at the prices it is currently available for (35GBP). The 150GBP price currently listed elsewhere appears to be a mistake as the RRP was only 100GBP so I've emailed the offender about it as a correction.
Who knows - much of the content of this box may introduce you to artists you really like but didn't know about. Now that unfortunately is where you may start to spend serious money.