I kinda reviewed it earlier, but yeah, it's good stuff. Played all the way through guitar on Hard, and played enough of Expert bass to finish the career. (It's setup a little differently than the past GH games--you don't have to beat every song to open up the next tier or complete a career.) I'll be starting on either Easy or Medium drums once I play some more Expert bass. I may even tackle vocals once I get through with drums (and if I ever get around to picking up a microphone.) It's also the first GH game to show you where you are in terms of stars (similar to what Rock Band does), so that's a good thing to have.
Songs themselves sound phenomenal and the setlist is fantastic--really centered on the
good old stuff. Something like six of the eight songs from Master of Puppets. The only song I'm missing is Jump in the Fire--it's got a great riff that would be really fun to play. Other than that, they hit on pretty much everything you would expect them to hit on--no complaints and even the non-Metallica songs are done well and fun to play.
I guess I should also mention that the difficulty is toned down quite a bit from GH3 (more like the difficulty in GH3 was an anomoly). It was really refreshing to finally be able to get all the way through One this time, instead of ******** the bed about 85% of the way in like what happens in GH3.
The extras are very well done and this is where GHM really blows the Aerosmith game out of the water. Many of the songs have what they call "Metallifacts", which is a trivia track that plays during the song, similar to Pop Up Video. Many, if not all of the songs have lyrics you can read, and there are several live performance and behind-the-scenes videos you can watch if you want. There's also a little picture gallery which is kind of cool.
My only real complaint with the game doesn't really come from a gaming perspective, and more as a Metallica fan, but aside from a few mentions in the Metallifacts, Cliff Burton and Jason Newsted are virtually ignored throughout. And I kind of understand why (they didn't want to slight the new guy), but those guys were important parts of the band's history (well, at least Cliff was, anyway

) and there should have been a little more about them. Not saying they should have been playable characters or whatever (that would be weird), but something more would have been nice. Like, I was going through the photo gallery yesterday and they've got all these group shots from the old days, where it's just James, Kirk, and Lars, and Cliff was cropped out. Why do that, you know? They arguably wouldn't be where they are today if it wasn't for him, so why go out of the way to exclude him?
Anyway, I'll wrap up by saying that this is easily the best Neversoft Guitar Hero game to date. Easily better than Aerosmith, much more fun to play than GH3, and the slight improvements it makes over World Tour makes it better than that game. I still don't know if it's worth $60 (I have a hard time paying that for any game these days, especially ones that don't feature---wait for it---exportable tracks), but it's great at around $40 or less.