James LaBrie trying (and mostly failing) to sing in a vocal range that he's not comfortable with; almost no bass guitar, it's like someone forgot to turn up the volume on that; one guitar less, Petrucci is great but even he can't do a 'wall of guitars' on his own; keyboards in songs that simply don't sound right with keyboards.
Bottom line: it sounds half baked, devoid of the passion and aggression of thrash metal. It's just great musicians going through the motions of covering a genre that simply doesn't suit their style. You'll probably like this album if you're not exactly keen on the original, if you're unfamiliar with the original, or you simply think Dream Theater sounds great regardless of what they're singing (eg. you're a DT fanboy).
Besides the astounding guitar work of Petrucci and drums of Portnoy (who drums this stuff better live than Lars did in the studio) this is just a version of Master Of Puppets with TERRIBLE vocals and 1 guitar missing.... and a silent bass guitar, can barely hear it. Not what I expected after all the stories I heard about this bootleg.