The song doesn't begin until 0:30. Listen for the following:
1. The trademark sound on the early Van Halen albums was the reverb on the guitar. Listen to how the somewhat dry guitar is on the left while the delayed reverb is on the right. It's also a very long reverb.
2. Eddie is a very sensitive player and this song shows him at his best. Listen to how intense he plays the choruses, but then backs off during the verses. I bet if he did this song again today there would be three guitar parts instead on just the 1: the chorus guitar, a verse guitar and another playing the fills. I like this one way better, as the entire part is a performance.
3. There's only a single overdub and that's during the solo, where a new guitar enters and switches sides. It's a bit edgier and has less reverb.