Skolnick in general is an awesome guitarist, and the best in the Thrash genre imo. And the best part is he doesn't have a huge ego or anything. Or at least I haven't noticed it.
One of the staple riffs of Opeth's song Black Rose Immortal sounds a lot like the main riff in In the Woods...'s Mourning the Death of Aase. Only Black Rose Immortal doesn't have a kickass vocal solo.