A lot of on-target comments in this thread. I really thought Pesci was extraordinary. Not sure why Keitel took such a nothing role, except I guess he didn't want to be left out.
I also agree that Pacino for once in the last 20 years underplayed a role - Nicholson's Hoffa was so much more electric. This Hoffa never had an air of danger about him.
One thing I liked that I haven't seen mentioned here is how DeNiro's character did his hits. They weren't dramatic, they weren't tortured. It was just a guy with a job in front of him that he did in the most workmanlike way he could. From the two Germans in the grave to Hoffa at the end, it was like a carpenter hammering a nail or a housepainter applying a brush stroke.