The choice to leave his mother at a young age continues to haunt Anakin throughout his life. He is plagued by nightmares of her and visions of her fate. When he eventually saves her from a group of Tuskens on Tatooine, his blind anger at her dying state consumes him.
All in all, Anakin felt incredibly betrayed by two of the most important people in his life. We all know he has quite the abandonment issues, and the fact that Obi-Wan and Padmé leave him is likely the primary cause of his extreme hatred.
Vader seems more stable, because his body was either concealed or mechanical. There was no face to display his contempt, no subtle shift of the shoulders or limbs to show his unease or anger. Even his voice was not his own, his biological vocal cords too damaged and weak to be of use.
Anakin admits to Obi-Wan that he has been arrogant and unappreciative of his training, and apologizes to his master. Obi-Wan assures Anakin that he is proud of him, telling him that he has become a "far greater Jedi than I could ever hope to be."
Not evil in a huge or defined way, just sort of evil generally. He was brought up as a slave and had to lose his mother at a young age. Given his longing for and obtaining for power he always had a contempt for democracy.
What Padmé knew about Anakin's previous dark deeds. Padmé was well aware that Anakin had committed dark crimes that would've started his fall to the dark side. He even confessed to her that he had massacred an entire Tusken Raider village to avenge his mother, leaving no one alive.
The canonical comic Star Wars: Darth Vader #7 confirms the younglings' deaths caused Anakin grief, self-loathing, hatred and pain, fueling his descent even further into the dark side. Those negative emotions also power the dark side, meaning Anakin likely felt stronger as he killed the younglings.
He slays Sidious and returns to Obi-Wan, begging for atonement by execution, only to be met with true forgiveness instead. But just as this fantasy Obi-Wan refuses to strike his former friend down, Vader refuses to turn his back on the dark.
First and foremost, Obi-Wan didn't want to have to confront and try to kill Anakin, we see this all the way until their final conflict in their duel where Obi-Wan pleads with Anakin to not make him do what he knows he'll have to do if Anakin tries to attack from the low-ground.
And so, Obi-Wan tells Anakin not to try it, because "he, just like Anakin now, had once been in a position where success requires a massive vertical leap over your opponent and he knew the risk that move entailed," as the Reddit user says.
In Star Wars Legends and Canon, Galen Marek (Starkiller) is the only Jedi (other than Obi-Wan Kenobi) to put a beat down on Darth Vader/Anakin Skywalker. Galen was secretly trained as a Sith Lord apprentice to Vader, but returned to the light side and the Jedi.
Darth Vader #26 finally addressed Anakin Skywalker's animosity towards sand -- by turning it into the embodiment of the Sith Lord's greatest fear.
As soon as Anakin Skywalker became Darth Vader, he already faced his most persistent nemesis and lost, namely his own master, Obi-Wan Kenobi.
Obi-wan regrets are layered. He regrets training Anakin and him regrets failing to train Anakin. He regrets hurting Anakin and he regrets not dying there.
Obi-Wan knew Anakin through and through and understood his overconfidence and arrogance. He knew Anakin would fight with rage and aggression, while he remained cool and calculated. Pairing his understanding of Anakin with his knowledge of Soresu ultimately gave him the upper hand in the battle.
Although the decision to turn to the Dark Side was Anakin's alone, the choice did not come from thin air. His natural prone to impulsivity and emotion without the support systems he needed in place made it easier for Anakin to stumble down a path of darkness.
Obi-Wan knew it was only a matter of time. So, he made the difficult decision to use his learnings and become one with the force, rather than let Vader decapitate him.
In the duel, Anakin lost both of his legs, his one remaining organic arm, and suffered (possibly up to) fourth-degree burns across what was left of his body that were severe enough to damage his internal organs.
On a practical level, Obi-Wan did not know that Anakin had survived simply because he was isolated on Tatooine. Although Obi-Wan did not see Anakin die after their battle on Mustafar in Star Wars: Revenge of the Sith, he reasonably could have assumed that Anakin would die from his injuries.
A very crucial scene in Return of the Jedi established that Obi-Wan Kenobi (a Force ghost by that point) blames himself for Anakin's fall to the dark side. He explained to Luke, “I took it upon myself to train him as a Jedi.
Anakin does not have even the slightest bit of remorse. By the end, he feels nothing but anger. Although he feels regret for killing Padme, he still helps the evil Emperor. The film ends with Anakins standing side by side with the man on whose behalf he has committed all his crimes.
Yes, his entire character since then was a self loathing tragic monster who has little reason to care about anything. Betraying Mace Windu instantly made him regret his act of impulse, Padme's death and rejection of his actions later on made it stick.
The short answer is yes, without a doubt, Vader regretted becoming a cybernetic monstrosity. First, there's the constant pain and discomfort from his suit. Worse, however, is the psychological pain. Vader destroyed everything he had ever known for a chance to save Padme.