I just watched it and found it no less than fascinating. The back story is equally as fascinating as the film itself. I wonder if the OP has seen it yet?
"I don't think there's anything extraordinary about me except this passion for the truth."

"The Boss, described in Wells treatment -the boss is not intended to be a caricature of a Fascist or Nazi leader.He is something more ancient, more modern and more universal than any topical movements
Richardson ignored the authors advice; I was a picture of Mew-soh-lini, because there was no dictator before Mew-soh-lini"

• Quoted from Christopher Frayling's 'Things to Come'
  If you want to see just Richardson's parts in the film they are on Youtube somewhere
  "I'm not sure I can watch anymore. No, wait, I can. I can."

Interesting post, blueradiance. For some reason or another, I still haven't seen this film since I first posted the original message a few years ago. I think I might go ahead and get a copy of it. I would hate to miss out on a good performance of Richardson's, even if the movie itself is not all that great.
I've never read the Wells story. When you say that Richardson went against Wells' wishes, what do you mean? Out of curiosity, what did Wells' originally want?
(By the way, as the second poster recommended, I did see Richardson in The Fallen Idol and thought that was a great performance and a brilliant film. I'd highly recommend it to all.)

I wouldn't call Richardson 'unimpressive' at all! His role was the most interesting, and the second act verging on fascinating. Richardson, going explicitly against H. G. Wells orders, based his character on Mussolini and stole the show.
The film is visually spectacular, but the story drags. Richardson's Rudolf is the highlight, it's all downhill from there
"I'm not sure I can watch anymore. No, wait, I can. I can."

It's worth a look for the curiosity value of seeing a vision of the future made in 1936, as well as for several moments of unintentional hilarity and some extravagant production design in the last half hour. Unfortunately, Richardson appears only in the middle section of the film, which depicts mankind reverted to the Middle Ages, and this is by far the least interesting section of the film. I found the acting, direction and the script to be quite poor. Richardson's performance is unimpressive - there's no opportunity for subtlety here, so he just hams it up royally. He seems not to be taking the thing seriously - perhaps the only reasonable response to such a silly script. In doing so, he comes away with his reputation intact, despite having delivered a performance that I found disappointing to watch. Whereas I don't think I will be able to take Raymond Massey seriously in any other film ever again.
For a Richardson fix, get The Fallen Idol instead, if you haven't already.