In Guitar Hero, the object of the game is to play one of five coloured notes that scroll down the screen. When a coloured icon reaches the bottom of the screen, you "play" it by holding down the same coloured button, and then strumming the bar with your other hand. It is a really simple concept that works really well, and it's the same story for the drums (you hit the correct colour when the icon reaches the bottom of the screen, and push down on the awkward foot pedal when a purple bar appears). When using the microphone however, you instead have to sing along to the words that appear on the screen. A graphic will show you the approximate pitch you have to be at and the game works out what pitch you are singing, scoring you on how well you compare.
In this version of the game, there are a helluva lot of songs. These are all unlocked by playing through the career mode,where you play gigs in a specific location from around the world. As you progress, the songs get harder and you'll end up playing several songs in each gig. In the previous game, you could also "purchase" bonus songs using an in-game currency, but this time you'll have to unlock them all through the career experience.
Career mode can be completed in a group of four as well, which is where the game really shines. With one player on lead, one on bass, one on drums and one on the microphone a great social experience appears, and ensures that you can have a lot of fun when not on your own. You play through career as you normally would here, with the only difference being the order of the track listing. If you've not got enough friends or instruments though, there is the option to team up with others online, and play through songs in co-op mode that way. Another notable addition to quick play mode this time is that when you change difficulty, you keep the set list you'd already unlocked, and you only have to start from the beginning again if you're playing a different instrument, which is handy, because the next time you're stuck on a particular song that you just can't do, you can recede to easy mode to give it another shot.
There are some new features too this time around, with the custom features being one of the most notable ones. Using a new music studio, you are able to create your own songs, by either playing notes on the guitar "live", or recording them step by step. There are lots of options here, and those who know what they're doing when it comes to music will get some enjoyment out of this, though many will find it tasking and awkward to navigate. There are some simple freestyle options available, but people may be put off by the difficulty of making a good tune. If you're no good at creating, there is the option to download other peoples songs for free, which is a great addition that you should use often. In addition to this, you can also create your own character and band logo.
One more thing to note is the online features. If you are not online, you will miss a lot of the overall game by not playing online. There are several online multiplayer modes available (face-off, pro face-off and battle), but finding a game can often be a pain, and the face-off mode feels a bit pointless. Rather than this mode, an in-game leaderboard would have sufficed much better, but when you add in GHTunes, the music store and the variety of co-op modes available the game just wouldn't be the same without these beneficial features.
Overall, this game is damned excellent. It almost feels as though they haven't left a single thing out, and despite minor niggles, this could very well be the definitive music experience on Wii. Just about everyone will enjoy it and there's plenty to keep you busy, especially if you're online.