I talked about ANH, but people had mentioned Vader in ESB as being particularly weak as a villain - again, let the kid in 1980 have his say...
Vader was the guy - now indisputably in charge and looking shiny and cooler for it (the grimy thug has been promoted in more ways than one) - who walks up and says with 100% certainty he knew the rebels were on Hoth - like he magically "sensed" it, even if the information at hand didn't prove it. And he was right. Oh, and he had the most badass ride of the whole Empire - this huge arrowhead shaped spaceship (called Executor,) and he doesn't hang with anyone - he's this scary loner that everyone onboard is terrified of, watching him leave rooms as if they're relieved he didn't kill them.
TALK ABOUT FAILING UPWARDS - NO PUNISHMENT FOR DESTROYING THE DEATH STAR?
Vader's sensing of this meant the Empire had found the rebel base. Had Han not investigated the probe droid and it had self destructed without that contact, Vader's actions could have led to a surprise attack that would have wiped out the rebellion.
SO VADER'S PROBES FAILED
Vader is obviously more ruthless toward Imperial underlings in ESB, killing them one after another for stuff that we'd think should just be a demotion or something. And he does it with either raging threats or that sweet Vader sarcasm - "apology accepted." Like he takes pleasure in it. One he even kills seemingly from quite a distance away, upping his powers in our mind - Ozzel's killed seemingly hundreds of feet from Vader, not just across the room like in ANH.
LIKE TRUMP, HE SURROUNDS HIMSELF WITH ONLY YES-MEN
Vader also wastes no time in getting to the Hoth battlefield - his hologram with Veers basically proves that Vader is on the first ship to land once the shield generator is down, and he's like the second or third person to enter the rebel base. While Han gets away, it's only just barely. Had Vader arrived just a minute or two earlier, it's likely he would have captured the Falcon and all those aboard.
AND YET HE FAILED AGAIN
So he starts the close chase and when his officer says "asteroid field" like "we can't..." Vader says "yes we do." Leading these huge ships into a super-dangerous chase through an asteroid field, which blows up their ships and creates chaos and mass death for the Empire. Vader's the spirit that drives that chase - with both star destroyers and TIEs getting pulverized, thousands dying, solely because he said "we continue" and importantly, nobody says no to him. They beg him - "Considering the amount of damage we've sustained, they must have been destroyed" and he says "nope - they are alive" and commands them to keep going.
RACKING UP YET ANOTHER EXPENSIVE IMPERIAL EXPENSE BILL
Then he's bowing before a hologram of this cloaked monkey-eyes guy we know nothing about, who seems to know a lot about what we have seen - Luke, the force - suddenly setting up how super-important/possibly powerful Luke is, but Vader also promising that - regardless - he will kill Luke if he won't join them.
AGAIN, FORESHADOW OF A FAILURE
Then on Dagobah Vader appears in the cave with snakes and hissing lizards, which is like a dream/nightmare, but not - Luke sees it and Yoda seems to sense it. Was Vader really there in some way, or did he controlling or sensing it? Did he place Luke's face in the Vader helmet, or did Yoda? We didn't know. At this point he was supernatural, or connected to something supernatural, but either way it was super evil.
THIS WASN'T VADER AT ALL
And then Vader before Fett and all the bounty hunters, these scary looking people bring huge rifles onboard a star destroyer and yet Vader confidently strides around right in front of them, in charge, even warning the baddest one and getting up in his face. And you can see that the bounty hunters were all Vader's idea by Piett's reaction, not Imperial procedure at all - his own men failed, so he went to scummy hunters because he knew they could deliver. It says that Vader is as much like those scumbag hunters as he is a member of the Empire.
VADER THROWING MORE GOOD MONEY AFTER BAD
And they do - Vader's bold, unconventional (ie not Imperial protocol) idea pays off, just like finding the rebel base on Yavin in ANH.
AT THE EXPENSE OF THE DEATH STAR
The next you see Vader he's side by side with Fett, having arrived on Bespin the day before and forced the whole deal on Lando. Vader gets everything now and he's all gleeful sarcastic again, inviting them to sit down to a meal with him. And when Han, the most badass gunslinger in the galaxy, draws and shoots, Vader literally just puts up his hand to block the blasts, then tugs the gun into his hand. No lightsabers or bodyguards needed. Vader barely lifts a finger. Our badass Han is humiliated, and in front of Leia and Chewy.
OK - THIS IS ABSOLUTELY A BAD ASS SCENE - CAN'T EVEN MAKE A JOKE... ALTHOUGH HOW DOES VADER DINE WITH THEM?
Meanhwile, Yoda and Ben are begging Luke not to face Vader - because he's so dangerous. So we're REALLY worried about Luke now, not just his life but he might fall under that Vader magic from the cave and become somehow evil himself. That whole "join us or die."
THIS IS ALL ABOUT LUKE'S FAILURE... WHICH IS A WHOLE OTHER THING
And to draw in Luke, Vader literally tortures Han. Not behind a hissing door like with Leia in ANH, but Han screaming and broken over a torture device (later he literally has to be carried to his cell) - right in front of us - as Vader watches just a few feet away, seeming to enjoy it. Meanwhile he's clear with Fett and Lando who's boss, both having to back down even as they try to stand up to Vader - Vader threatening Lando over and over.
THE MAN PICKING ON THE LITTLE GUY... DOES NOT MAKE YOU BIGGER.
And for Luke, Vader's idea is to freeze him in metal to transport him to that evil hooded monkey-eyed guy we barely know but is evil as ****. It doesn't get much more brutal than that (he calls Luke a "prize" for the Emperor) - and, not even knowing if a human can survive it, he tests it on Han, saying to Fett they'll "compensate" him if Han doesn't survive - again, pretty brutal. Like Han's a piece of meat.
HE KEEPS HIS PROMISE TO FETT.... WEAK MOVE FOR A BAD ASS VILLAIN. JUST KILL FETT.
And then in the showdown, Vader majorly hands Luke's *** to him, leaving our hero Luke in shape that traumatized all us kids - bloody, bruised, handless, broken, then.... he drops that daddy bomb. Luke does the best he can (knicks Vader's shoulder, does a cool jump) but Vader gets tired of playing with the mouse, lowers his saber and just uses his mind to pound Luke with heavy equipment and sends him through a window. There's also that great moment where Vader "flies" down from the carbon freeze chamber like this black raven, cape blowing.
UNTIL HE COUGHS FROM GETTING A LITTLE STEAM BLOWN AT HIM, AND THEN MOMENTS LATER FALLS BACKWARD OFF THE PLATFORM
Even as Luke is rescued, Vader again surrounds them and then talks daddy again - with his mind, directly into Luke's mind (like this guy's powers are getting scary - he can talk inside your head from a mile away) - even as Luke's got a medical stump where his hand used to be. They get away, but only because again, things beyond Vader's control (Vader smartly thought to deactivate the hyperdrive) save the day.
VADER BEGGING. SAD.