A GREAT GAME FOR ANY METALHEAD!!
It's been a long wait, and I must say, the greatest out of all the Guitar Hero Games..
Guitar Hero Metallica has all the same features as World Tour, and includes 30 of Metallica's best songs, and over 20 guest acts: Lynrd Skynrd, System of A Down, Mastodon, Slayer, etc.
It also has some great DLC packs with awesome songs.
Also, if you want more of a challenge, THERE IS NOW A DOUBLE BASS PEDAL FOR DRUMS! It makes it more intense which is cool.
As far as Achievements go, they're fairly easy to get. Most of them are named by Metallica songs, which is cool. There's no Guitar Battles this time around, but thats not much of a problem.
If you are looking for a Guitar Hero you can actually headbang to
GUITAR HERO: METALLICA IS WHAT YOU ARE LOOKING FOR!