If you have already discovered Bujold, and are still in the stage of trying to acquire copies of everything she's written, then you might be frustrated by the reissue volumes, each of which includes two novels, and frequently a novelette. This volume includes The Warrior's Apprentice, "The Mountains of Mourning" from Borders of Infinity, and The Vor Game. Thus, there is nothing new here for the collector. On the other hand, this makes an excellent introduction to Bujold's work for the newcomer, because it introduces Miles Naismith Vorkosigan as he first creates his alter ego Admiral Naismith, then gives some revealing insights into his Barrayaran background, and finishes up with Admiral Naismith being given a permanent role in his life. Many of the later Miles books, while excellent in and of themselves, probably won't have as much resonance as they should have if you do not have this background in mind. (Which is not to say that these are something you need to suffer through to get to the good stuff. The good stuff starts right away. Why are you even wasting time reading this review? Read the book!)
Note: the other reissue volumes are Cordelia's Honor, which includes Shards of Honor and Barrayar, and Miles Errant, which includes Cetaganda and Ethan of Athos, as well as "Labyrinth" from "Borders of Infinity."