It looks like a video game cutscene now but back then when we only saw a Muppet it was a huge step up.

I'd disagree with that. The surface of his face looks like it has totally different quality and texture to anything that's actually captured on camera. CGI isn't always better look at CGI Jabba the Hut from the New Hope edits

Also it doesn't undermine is character at all in the OT, it only adds. It would undermine is character if he fought like that after he told Luke about not fighting but he told Luke that only because he himself failed because he did fight. It's called character development, like a grand Master Jedi wouldn't use a saber during the galatic republic?! That would be more strange than anything, he isn't the hermit who lost so much that you see in the OT. That is why it's called a prequel, it shows how characters came to be in the OT.

I'm not saying he can't be at a different stage in his life or do surprising things. I just think the blackflips are stupid and needlessly negate his (up to then) frail nature. He could have used force lightning or telekenisis like the hugely powerful emperor in the OT, or they could have shown him using some other new power which fits his character (which would have actually been surprising and kind of welcome given the Jedi and Sith together only have about half a dozen special abilities going for them). I would even settle for him a duku having a more reserved lightsabre duel like old ben kenobi vs darth vadar on the death star.

I'm fine with him having an extended character arc in the prequels, but instead of developing this by showing him climbing all over duku like a pet weasel they should have served this by actually giving his prequel personality a sense of humour and mischief like his OT personality so that it doesn't feel like they're two totally separate characters. If he's such hermit who's lost everything, why do we see him acting more carefree in Empire Strikes Back than we did in the prequel trilogy?