Even if you're a major Metallica fan, be wary of this title.
It has the same positives and same negatives as GH:WT (Gasp! Shock! Surprise!). I would say the charting has "improved" but there are still a decent number of songs that are charted like Activision just doesn't care for accuracy. As long as it's in the ballpark, we're good.
The Expert+ mode is a pretty cool addition if you happen to be a drummer and are actually awesome enough for double bass pedals. Sadly, my left leg isn't quite as adept as my right, but it's a fun mode nonetheless.
The solos are still pegged away with mashing random buttons instead of using the touchpads, which is a shame.
The character models you can tell are the members of Metallica, but I hate them. I dunno', it's a REALLY messed up jaw here, too big of a head there, the fact that I hate Rob's hair in real life let alone in game over there. Oh, and Lars is king douchebag now and forever.
There's a great selection of songs, honestly. The Metallica tracks are all very well thought out and chosen. I wish there were more Garage, Inc. songs and Hero of the Day was included, but I can deal with it. Fade to Black, Master of Puppets, Wherever I May Roam, and Hit the Lights make the Metallica side of things awesome. Then you have Mastodon, Bob Seger, Queen, and Judas Priest to make everything else bad-ass too. The game itself still suffers from the boring presentation and bad charting, though, so hey. I'd go into detail, but I already wrote a review for GH:WT, so read that.
In summation: Rather than take their times to craft a truly satisfying rhythm game, It's like Actvision is more banking on the fact that's called Guitar Hero and the fact that coupled with their hall of fame induction, Metallica could sell dirt right now. They have some great ideas for the genre, honestly, but the execution is failing them over and over and they're not really caring enough to fix said problems. Why? Because they're making money. Which, I don't blame them on that basis, but this is MY review of the game. Its audience is too narrow for a game that really isn't THAT enjoyable to its target audience anyway. Give it a rent, if you love it enough? Buy it. But I strongly warn against rushing to the stores for this game.