I'm generally against such releases - they show nothing new and in most of the cases the reproductions are few times worse because of the band's inability to play as aggressively as all those years ago. However, there are little exceptions to this rule, such as this album. And though Testament's albums didn't need refreshing, this small experiment turned out to be a nice glimpse into the past.
The problem is: not all the songs got improved. Obviously, the thing to change was the heaviness of the songs as the latest Testament's releases reached a completely new level in sound, which made it sound very heavy and death metal-like. This let the classics like "Disciples of the Watch" or "The Preacher" far more "thrashy" than before. However, it also made the songs from "The Legacy" album less aggressive, a bit slower. Their value was also diminished by the vocals, which just don't fit the music. These are not good examples of high quality of the re-recordings.
Playing those old songs differently was a good idea and generally it went good, but the thing to change was the set of the classics so there would be less "The Legacy" and more "The Ritual", for example. Or play them differently, which seems hardly possible for a band staying alive for twenty years and collecting the old line-up again.