I assume that the costumes and weaponry are accurate or close. I am not even bothered by the fact that some of the events are clearly fictional. I am, however, uncomfortable with the license that was taken in some specific instances. There are some elements that seem to be exaggerated strictly for their emotional impact. One or two elements felt so exaggerated as to be severely distorted.
Shock value is appropriate for horror movies or action flicks, but it ruins a straight drama.
That line between the sublime and the ridiculous is crossed. And once that line is crossed, all is lost. And it's all true. My personal theory is that Americans don't particularly want to think of the British as villains. One evil mastermind with an English accent is fine, but in this case we fought the entire country.