I'm slightly disappointed with the new stuff, actually. Sleepwalker has some good moments, but just doesn't do anything for me the way a song like Holy Wars...The Punishment Due or Architecture of Aggression do. I like the verse/chorus of sleepwalker, but the vocal rythm seems off to me, like he's trying to fit too ,any syllables into the song. The bridgey end part was good, I just didn't like the way it fit into the song as a whole. Maybe I'm being too hard on them, and expecting them to be too much like they were in the past.
I'll still buy the album though, just because Megadeth is one of my favorite bands, and because I think there will be some excellent songs on there - Gears of War and Sleepwalker won't be the whole album, I'm sure.