Cromwell is a fascinating character !
Very complex man !
That period of English history is also very fascinating and an important influence on America. Many issues that period brought out we saw reemerge here during our Revolutionary period and even to this day. The different factions that formed in the parliamentary army discussing government, the rights of man, religious rights vis-à-vis personal conscience and government, his right for a voice in government we hear the echoes today. For example consider the Leveler movement.
I think the movie - Richard Harris does a good job of capturing Cromwell’s personality. The history as Hollyweird always does is distorted. Hollyweird writers always convinced they can do better drama then history!