Eh, I take the movies for what they are.
People always play up Palpatine like he's some great, all-powerful Sith and completely disregard the other great Jedi. Palpatine's true power is patience and calculation, in my honest opinion. He spent many decades planning out his conquering of the galaxy and the Jedi.
Don't get me wrong, he was a powerful Sith, but I will never buy into the fact that he could have taken out either Yoda or Mace on his own. It just makes ALL three characters boring and pointless to me, during the Prequels, if I accept Palpatine as some bloated, unstoppable villain.
He was an old, tactical Sith that could manipulate people and electricity. Oh, and he could use a saber with the best of them.
As for the face aspect of the character. Yeaaah. Sith can suppress their Dark Side eyes, but a human masking his entire face in some convoluted dark side manner is an area I just don't think the films would explore. I'm pretty sure George was speaking metaphorically and didn't literally mean Palpatine was that hideous before the battle.
That's not to say suppressing your inner Dark Side when always in close proximity to the Jedi isn't a feat unto itself though. There was only one instance I can recall where anyone might have even suspected him before episode 3 and that was Yoda, in the scene from AotC where Palpatine is making his plea to Padme and spits out the very thing she's about to say, word for word. Ultimately, he seems to brush it off as coincidence because he couldn't sense anything from him, I think.
Anyway, it just plays out more theatrically if Palpatine is a flawed character and not some uber villain, in my opinion. And I much prefer Mace having ****ed up Palpatine's face to some half-cocked idea of illusionary Sith magic.
Oh, one last thing. Palpatine didn't let Mace win. Even with his foresight, there were no guarantees that Anakin would show up in time, much less kill Mace. Anakin came there to make sure Mace simply arrested the chancellor. What happened had to happen. However, before Anakin shows up, Palpatine was pretty much giving Mace everything he had.