Slipknot

but the album was downloaded a long time ago...

I downloaded it on the same day it was released on Slipknot's website :).
Honestly, at first, I didn't like the album... but then I listened to it and realized it's great! It's not like the previous ones... You can feel the uniqueness.
Almost every song is at least five minutes long :).

I used to listen to them...
but unfortunately, Slipknot has become so mainstream that I'm embarrassed to listen to them.

Where did they become mainstream???
Personally, I think they get better with each year... Well, Vol. 3 is definitely better than the previous albums :).

listened to it a couple of times - I don't like it.

That's why I advise you to listen to it more :) at first, it doesn't appeal to many people :).