Van Halen is described as legendary but this game isn't but just simply fun.
The game doesn't include the Guitar Hero 5 gameplay but mainly the gameplay from Guitar Hero: Metallica. The thing that's missing in this game is a category of videos whether Van Halen really did motion capture or some people hired them.
The songs in the game are mostly focused on big rock hits not bands that influence Van Halen. Songs like The Offspring's "Pretty Fly (for a White Guy)", Tenacious D's "Master Exploder" & Judas Priest's "Painkiller". This is because Wolfgang Van Halen (son of Eddie Van Halen, current bassist and 18 years old) chose the songs for the game.
The game's career is, like Guitar Hero: Metallica, focused on venues that Van Halen previously performed in such as New York City, the Netherlands & London. These venues have some history with Van Halen like recent tour, birthplace, etc.
The motion capture is very unique. Eddie Van Halen's famous instrumental "Eruption" is included in the game is pretty much the hardest of all. In the song, Cathedral, Eddie's avatar simply did hammer-ons and turn the volume knob on and off. In "Spanish Fly", Eddie's avatar use a nylon-string guitar and simply did a lot of tapping.
You may have to ask a friend who owns the game if it's good but feel free to buy it if you just want some fun.