Don't get me wrong my little.jab at Steve Harris was completely with respect to him. I am a huge maiden fan. Steve's gallop style is iconic. And like you said, simple, but hard to do well.

Public_N_M_E

I wanted to suggest something different to the more obvious Metallica (a defining element in their songs to my mind) or Iron Maiden (yes, simple but hard to execute well and very effective).

carlosfandango

Meta Music Mondays - Bass, dirty stinking bass!

There's some really cool elements there. A lot of metal is quite basic from a bass point of view. (I'm looking at you Steve Harris, I love ya and simple can be effective, but it is still simple). Bassist used some really cool funk style concepts in this track, especially whilst mirroring the guitar during the 1minuteish mark. 

You're right, it's not easy to pick out but it's there.