I echo much of Cajunscot and everyone else. Julia Roberts & Aidan Quinn need to avoid accents, though his was more consistent. While older, Neeson looked so much like the Big Fella that I found it eerie. Rickman was a bit short for Dev, and I found his performance chilling. It looked very authentic and felt pretty darn real.
Except for "Darkman", Neeson seems to pick quality projects, much like Daniel Day Lewis.
Collins wore a number of hats throughout his career and made the Intelligence function for the rebels far more effective than it had ever been. This, of course, was depicted in the film.
It is an emotive film for those with the slightest link to Irish history. I'd like to see Peter de Rosa's "Rebels" put on film.