Have known the Zeppelin catalog literally my entire life, and this is a worthwhile addition. It shows that there's definite potential with Zep, and this was without the multitracked guitars of the studio records. It's criminal that this is really all we've got in surround from them, the mix is so conservative on Song Remains the Same that I can't in good conscience count it as surround.
That said, it's not great quality that they had to work with. DPLIIx *Movie* upmixing to 7.1 helped add clarity by removing a bit of mud from the mix.