The problem is, in 2010, superior live versions of many of these songs have shown up on other releases. Kinda steals the thunder. In 1979, I would guess it was a thrill to hear these live versions of "Sugar Mountain," "I Am a Child," "After the Gold Rush," "The Needle and the Damage Done," "Cinnamon Girl," etc., but nowadays you'd be better off checking out the versions on the archive series, or from the MTV Unplugged version, and so on. On the other hand, the performance of "Tonight's the Night" here holds up pretty strong, and "Like a Hurricane" is an improvement over the album version.
So maybe some of the performances are not the best/most/polished/most soulful live versions available. In particular, Neil's voice lacks its usual punch on much of the album. Perhaps it's not the great, essential album it once seemed, but I think there's enough strong material on here to warrant serious attention. I've mentioned before that one of the joys of live Neil Young albums is the way you'll hear a reworked version of a song you maybe never cared for much in the past, and suddenly it will click and you'll realize what an awesome song it is. I think the winner for "Best Redemption" on Live Rust is the upbeat, rockin' version of "The Loner," which was originally a middling little jam on his self-titled album, that later showed up in a respectable acoustic version on 4 Way Street. Now, given the Crazy Horse treatment, it kicks all sorts of ass.
Though lacking in the poignancy and intimacy of some of his best live albums, I'd say the main strength of the album is the joy of performance it exudes. Even songs I'm not normally crazy about, like "Sedan Delivery," benefit from the live energy. There isn't any goofy small talk like on Sugar Mountain, but there are a couple of odd little interludes (one part where he pretends like its raining, a bit where he talks about how he'll buy an electric guitar when he gets famous, and so forth). Most fun are some of the vocal flourishes that Neil and Crazy Horse throw in here and there, for instance when, during the finale of "Cortez the Killer," everybody adopts inexplicable (Jamaican?) accents: "He came dancin' across de water, man!"
The other fun part of a Neil Young live album is that you usually find a few lesser known, neglected songs thrown in for good measure. I noted earlier that many of the songs can be found on other live albums, but keep in mind that that is somewhat counterbalanced by the presence of "Lotta Love," and a solo version of "Comes a Time."