Yes, he is indeed an immensely talented actor.
I must confess, though, I'm not sure if I've ever seen him in anything other than Sideways.
Because he is such a great character actor, you might not recognize him. These are just a few major films he's been in besides the ones I mentioned:
Saving Private Ryan
Paycheck
The Truman Show
The Negotiator
My Best Friend's Wedding
Donnie Brasco
He's slated to be in 5 films coming out this year and in 2006:
Cinderella Man
Robots
The Hawk is Dying
Any Bully
Paper Man