Gandalf the Grey and Gandalf the White
And Monty Python and the Holy Grail's black knight
And Benito Mussolini and the Blue Meanie
And Cowboy Curtis and Jambi the Genie
Robocop, The Terminator, Captain Kirk, and Darth Vader
Lo-pan, Superman, every single Power Ranger
Bill S. Preston and Theodore Logan
Spock, The Rock, Doc Ock, and Hulk Hogan
The 4K trilogy (4K77, 4K80 and 4K83) are original theatrical film scans by enthusiasts. Where Despecialized manually recreated the originals by using multiple sources to restore changed scenes, the scans are just that. The results are ultimately very similar.
The main advantage to Despecialized is that it uses the official 4K Blu-Rays as its source for anything that doesn't need restoring, so it's mostly a professional quality transfer, while the 4K trilogy were scanned and cleaned up by fans. The main disadvantage is obviously that Despecialized is not a "real" theatrical cut while 4K is.
Either will probably satisfy somebody who wants to watch the unmodified orig trig.
Vader was always there, it was just a matter of him being changed from the original actor to Hayden Christensen because he was more recognizable.
But in context, it doesn't seem to make much sense. Why does Darth Vader age down, while Obi Wan is still Alec Guinness instead of Ewan McGregor? If it's supposed to be reflective of the last time he was "good", why isn't it him at the moment he decided to save his son and kill the Emperor?
There's a couple of things people who don't like it criticize. For one, the Christensen footage is from an early test for Revenge of the Sith, so he's just weirdly glowering at the camera because he wasn't thinking about this moment when it was filmed. That's also why it's just Hayden's head comped onto Sebastian Shaw's body.
Then there's obviously the question of ... why Hayden Christensen at all? The implication is that the "real" Anakin Skywalker died decades ago and was replaced by Darth Vader, which kind of runs counter to the idea that he was ultimately redeemed by his love for his son as presented in the original cut.
Then you've got the fact that it kind of makes the original trilogy nonsensical in standalone. If you come to Star Wars and watch 4-5-6 first, there's some random guy you don't know at the end. It forces you to watch at least 1-2 and probably 3 first, or do something wacky like the Machete order (4-5-2-3-6), just so that the ending makes sense.
If you haven't figured it out yet, I don't like it myself. But I don't care because I've got the Despecialized editions, so Maclunkey it up.