My overall feeling was, and so what? Helen Mirren does a good job of portraying a sovereign discovering that, after fifty years, she's suddenly lost touch with her subjects. Serial bad guy James Crowmwell makes Philip mildly amusing, and at least looks vaguely like him, unlike Alex Jennings as Charles and Michael Sheen as tony Blair. Blair, incidentally, is portrayed as a saint, and Alistair Campbell as a thug. But the problem with this film is that it's a very sight story. It's not like Her Maj was likely to be massacred in a storming of the palace; she got bad press, then better press. That's about it.
The portrayals didn't engender much sympathy, either - the only people in the Royal Family I've felt sorry for over Diana are her two sons, and neither of them get a line in this.
Despite all this, it was nominated for Best Film at the Academy Awards. Hmm. One can't help feeling that that's the U.S. Disney-esque fondness for the British Royal Family at work, there.
Personally, I think this film would have been much better if Spitting Image had made it.