IF your talking about the fast power chord chugging, its gonna be pretty darn hard to use your fingers (especially over 3 strings) and palm mute at the same time, so I highly recommend using a pick. You can finger pick the solo, but that takes time and dedication, especially if your new to finger picking. IMO, metal should be played with a pick, unless its an acoustic piece, then by all means use your fingers. As I said, that my opinion, do whats most comfortable to you.