I found it particularly interesting because of the way it progressed.
Yoda walks in nonchalantly and effortlessly knocks out the two red guards as if they were mosquitos. ( I absolutely loved that part too. I get the biggest grin on my face everytime I see it

Palpy looks amused at Yoda's appearance and gives the impression of "HA! So now the aged warrior plans on giving me a spanking does he?"
In fact the irony here is that he accuses Yoda of arrogance and then blasts him with a single bolt of lightning that mind you, DOES catch Yoda off guard (not sure why, he should have expected it). He did not crank up the power and keep blasting away until Yoda was turned into a messy green stain on the carpet. He stopped and just laughed at Yoda in a manner that suggests "I have nothing to fear from YOU. I can kick your little green ass from here to Dagobah".
What I find really interesting is when Yoda stands up and then gives it to him in a very powerful force blast that was strong enough to get a gasp of pain out of Palpatine, and blow him backwards enough to actually unceremoniously land upside down on top of his chair.
Now look carefully at his face when he gets to his feet. He actually looks surprised and a little scared. And what does he do? He tries to run out the door. That's when Yoda flips in front of him blocking his way and says that line. "If so POWERFUL you are.....why leave?" *green lightsaber ignites*.
Now this is where Palpatine looks at him and starts a slow smile as he says (almost as if he is realizing it), "You will not stop me. Vader will become more powerful than both of us".
So up to this point I want an indepth analysis here and see if anyone has a different take on it than me.
My take is this. Force blasts give an indication of the strength of a Jedi or Sith, and until Yoda actually demonstrated his power to Palpy, he did not truly expect Yoda to be anywhere near that strong. He has also had many decades of direct contact with him and Yoda was seemingly "retired" as a council member and teacher more than a combatant, and I think it's reasonable to assume Palpy thought he was too old and feeble to still have great power.
So when he was effortlessly thrown back like that, I think he panicked a little and thought he might have been a little too arrogant HIMSELF.

I think when he thought about Vader though, he was basically bolstering his own ego enough to think, "Hell, I just converted their most potentially powerful member of the Jedi order and he is MY apprentice, so it's all good".
Now when they start the saber duel, it's a situation that probably changes the measure of each other anyhow because the Emporer channels his hate and anger in the fight and therefore doesn't let any misgivings enter. He probably fights like an indomitable machine until checked.
One thing that annoyed me about the movie though, is that it didn't show how Palpy got the upper hand on Yoda when he was flinging pods at him. They were fighting on the same pod until they return from the other duel going on between Obi and Ani. Then all of a sudden Yoda is further below him, and dodging all the pods.
In any event, my take on the saber fights between them are this. Yoda and Palpy are too evenly matched for whatever reason. Maybe the Artoo form Yoda uses is not effective in penetrating the Emporers style, and conversely, I do believe the Artoo form is one of the better defense mitigation forms because you are bouncing around so much you are harder to hit. So saber fight between them is a useless point.
However, the force is the big kahuna here, and the last major battle between them is again very telling to me...
Once Yoda is face to face with him again and Palpy blasts him with the lightning, Yoda demonstrates his ability to counter these blasts. How he does it exactly I would like to know, because I don't think it's truly explained...but again my take would be this:
Yoda catches the lightning in a way that doesn't exactly deflect it....doesn't just absorb it and dissipate it...but seems to hold it in abeyance. It seems like the energy is being almost "stored" in a type of power void that can be expanded to a point where it can be "released" as a weapon. This seems to be indicated by the fact that when Yoda is holding his own and faces him with that look in his eyes that says "You miserable little fucker...I am so going to shove this lightning up your ass"..the Emporer's face changes..he starts opening his mouth wide and makes some noises like "oh....ohhhHHHH" and to me it looks like he is feeling a buildup of a return volley that is starting to freak him out. When it happens, it looks like the blast is aimed at him and quite effectively smacks him, but Yoda also gets the kickback effect and IMO is pushed a little further because of his size which in this case is highly unfortunate as it indirectly leads him to fall from the great height. Effectively ruining his chances at finishing the fight.
The real question is this. Forcewise Yoda looks to be easily a potential match for Palpitine, but HOW exactly could he have used his power to kill him? Lightning does, force blasts alone have never demonstrated this in the movies. If he could have continued the battle with Palpy, what direct applications of the force could he have used to kill him? He DID say "Destroy the Sith, we MUST", so he definitely did not intend to take him prisoner.
Phew. That was longer than I expected. Thoughts anyone?