"Ummagumma", a half-live, half-studio double album released in 1969 is one of the band's most underrated efforts - apparently the band don't think much of it. However it's wonderful.
The live tracks are atmospheric and show why the Floyd were such a highly-regarded live act in 1969 - they're nothing short of awesome here.
The studio album - half a side for each band member - is the bit that causes people problems - many regard it as unfocussed and self-indulgent. One reviewer once memorably described it as "four middle class boys trying to be avant-garde in their Sunday best". I prefer to look at it as the Floyd at their most experimental, a record that's sometimes a bit short on catchy tunes but one which rewards repeated listening.
This is an impressive remaster, with a lot of hitherto unheard detail subtly revealed. Not a good place to start for Floyd newbies perhaps, but a great album nonetheless.