Can't fathom how you saw those battles as horrible. They rehearsed the heck out of those things. You watch the special features and it's amazing the work they put into it. I thought they were second only to the Darth Maul Ray Park stuff.
The only weak acting I saw was from mostly H.C.
The climax is not the end to a movie or literature, but the height of the tension. I think you mean conclusion? I thought it was perfect. The twins are born, Senator Organa adopts one, the other goes to Owen/Baru. Palpatine uses the Jedi arrest as a means to create stronger martial law and declare the Senate an Empire. Great lightsaber duel with Palpatine and Yoda. The Vader thing was great. The "noooooo!" part was a touch corny, but the point is solid that Palpatine is feeding off Anakin's pain. The end of the film is perfect imho.
Plot holes? Well, most Star Wars films did have them. A New Hope had them. One minute Luke and Leia are sucking face, the next minute in Empire they're doing it some more, then in ROTJ they're siblings!? The clone army thing in Ep2 was odd and then later the storm troopers are average humans. Luke Skywalker trains with Yoda for about 10 minutes of his life and then in ROTJ on his own somehow he has 'arrived' as a Jedi LOL. In A New Hope you can tell Vader killed Anakin. Then in Empire it changes and "a certain point of view" kicks in. In Empire Yoda comments on how "now matters are worse." Obi-Wan replies that "That boy was our only hope." to which Yoda says, "No, there is another." Then later in ROTJ it is Obi Wan who knows about Leia and tells Luke. How could Obi Wan have not known about Leia when the two of them were born twins? Heck, Boba Fett, the coolest bad guy in movie history, was eaten and burped by the Sarlacc. Talk about lame-o! In Empire Vader could've easily stopped Luke with force power from falling from the tower. The list goes on and on.
There were definitely some plot holes in the prequels. Leia remembering her mom. How? Uncle Owen should recognize R2D2 in a New Hope because of the prequels. Vader should, too. There are plenty more. Frankly the Phantom Menace established most of the plot holes. I still like Sith though. Cool movie.
And the Ewoks were hardcore! The Jawas were frightening scavengers, and the rebels on Hoth laying in trenches against AT-AT’s was a good plan! 
Star Wars ships have loud sounding engines even though there is no sound in outer space LOL. If we’re going to get too nit-picky, it’s goofy....
