I'm not sure it makes sense to call it the "Holy Grail" because you could find recorded versions of the show if you knew where to look, but an official release of Bruce's legendary (and here, that's just fact, not hyperbole) show at the Roxy certainly qualifies as major news for anyone who even remotely considers themselves a fan of Bruce.
The show is famous for a few reasons, aside from the fact that it deserves to be on the basis of quality alone. In his Rolling Stone chronicle of Bruce's 1978 tour, Dave Marsh wrote about the show extensively, and one thing that has stuck with me through the years is when he mentions that Jackson Browne, Glenn Frey and Irving Azoff were all present at the beginning of the show, with Frey and Azoff leaving after a handful of songs and Browne closing out the night dancing on the top of the table at which he was sitting.
A year later, Greil Marcus wrote about the show for his New West column (congratulations if you remember that late, lamented periodical). Marcus was not present, but got his hands on a decently recorded bootleg of the show (I had one as well, but I'm not sure I'd call it a decent recording) and called it "one of the most vivid pieces of sound in the recorded history of live rock 'n roll. There's nothing you can't hear; even when the band goes after its harshest, most brutal rave-ups, every note stands out."
I've been to ten Springsteen shows, but my first wasn't until the 1980 tour behind the release of "The River," after he had graduated from the small clubs and venues to playing almost entirely in basketball/hockey arenas. Four years after that, he'd make the full-flown leap into baseball and football stadiums. I saw him at each, and loved every show, but there's no doubting that the sound you can achieve in a smaller venue is superior to what you can do in, for example, the cavernous Oakland/Alameda County Coliseum (or whatever they call it today).
When you listen to the Roxy show, you can't be faulted for thinking that you are listening to rock history. I've played the bootleg off and on for nearly 40 years, but there's no questioning that the sound quality on this release is far superior to what I shelled out $25 for back in the late seventies (and believe me, $25 was a lot of money back then for a vinyl record). For example, I'd never heard that show's version of "Point Blank," the same version he would play at Winterland in December of that year - not quite finished, not quite the version that you hear on "The River." But still amazing, nonetheless.
But the highlight, then and now, is the titanic version - played only a couple of times since the 1978 tour - of "Prove It All Night." I'm going by memory here so this may not be a direct quote, but Dave Marsh in describing it wrote something along the lines of, "When you hear this version of the song, you might question whether it is a hit single, but there's no questioning that it's a great song." I'd go even further than that, and say that the 1978 version of "Prove It All Night" - and don't get me wrong, there have been other great versions of that song - is probably the single best live song he ever performed.
One final note - a friend and colleague of mine was actually at this show, which is pretty cool. For me, that is. Very cool for him.