The main reason to obtain this recording is that this is the version premiered in St. Petersberg in 1862, with many differences from the more familiar 1869 revision.
1 - The prelude is mostly the same as the first few minutes of the overture. After the melody from Leonora's Act II aria, the remaining music is from the very end of the opera, when Alvaro commits suicide.
2 - Act I is mostly the same, except for the passage where Leonora tries to convince Alvaro to delay their elopement. It is quite lyrical, but not quite as dramatic as the revision. Also, a few small differences in the vocal line of the duet are noticeable.
3 - In Act II, Scene 1, Preziosilla's solo is in B flat rather than B, and it does not lead directly into the prayer that follows, as it does in the revision.
4 - Leonora's duet with Padre Guardiano in Act II, Scene 2, has several differences, most notably the passage where she begs him not to send her to a cloister. Overall this scene sounds like a less refined version of the end result.
5 - In Act III, Scene 1, Carlo's aria is in F, rather than E.
6 - The two portions of Scene 2 are in the opposite order, the camp scene preceding the duet. There are several portions of the camp scene where the feel of the music is similar, but the actual content is different. The dawn patrol chorus is not in this version. The duet between Carlo and Alvaro does not yet have the introduction for Alvaro alone; the two men appear to enter together after meeting for the first time since "Solenne in quest'ora." Otherwise, there are two passages which would later be cut, one of which takes Alvaro to a high C. The final version is tighter and less taxing on the singers, but the original is still extremely exciting. After the duet, the rest of the act is entirely different, consisting of an orchestral depiction of the duel followed by Alvaro's aria where he is horrified at apparently killling Carlo. Again, this is a very taxing passage, ending on a high C, but extremely exciting.
7 - In Act IV, Scene 1, Melitone's scene with the beggars is occasionally different, yet always similar in character to the revision. Carlo's solo passage before Alvaro's entrance is much shorter and less satisfying than "Invano Alvaro," but the duet itself is the same.
8 - In the final scene, very little of the music after Leonora's aria was retained. There is a brief duet passage for the reunited lovers leading to Leonora's murder by Carlo. She sings a brief, affecting death scene before the monks enter and Alvaro throws himself off the cliff to music heard in the prelude. It is certainly a much more grim, less cathartic ending than the revised version.
This performance is a very satisfying one, if not quite on the same level as many of the recordings of the 1869 version. If you can find it, there is also a recording of this version released in 1997 by Gergiev and what is essentially a Russian cast. While it is a bit more polished than this recording, the singers tend to be less idiomatic than the singers featured here.