I recently took a peek into what ended up happening with Spongebob Squarepants after I stopped watching it as a kid. There's some of the bummer stuff I expected to see - flop spinoffs, episode ideas that kinda scream "we're running out of ideas - but overall I was pleasantly surprised by how much the show seems to have kept its charm! Apparently the part where I stopped watching is A) a lot earlier in the series than I remember (probably sometime in season 6 or 7 or maybe 8?) and B) considered by many to be the low point of the series as a whole. All these years I assumed I stopped liking it because I got a little too old for it, so it was odd to find out that my "this show is kind of bad and gross now" assessment was actually supported by the material.
Anyway, one of the things I really like is how they have expanded Karen's character and iterated on her design. I find the new her really charming! During the period I watched she was always just sort of the punchline deliverer in a stock-standard "long-suffering wife in a loveless marriage" character dynamic. If memory serves she was basically Peggy from Married... With Children, but a robot. Which was fine, I didn't have any complaints about her as a kid.
However, in the years since, they seem to have pushed toward showing them in a healthier relationship that has struggles but where you can also see they like and love each other. I think that's so much more interesting, and a more fruitful vehicle for comedy. Making her a willing and active participant in their relationship, making "computer wife" mean "my wife who is a computer" rather than "a computer I built to act like a wife," gives her opportunities to do things other than roll her eyes at what Plankton does.
I saw a gifset from that tango episode and I love how it shows that she's evil too, a cartoonish schemer the same way Plankton is. It's just that she's more pragmatic and less impulsive than plankton, so she usually ends up following along with his schemes... but when she's put in a situation that she is also enthusiastic about? When they both have something they want? They both set about ruining everyone's night in perfect synchronicity. They don't even have to say a word. It's so cute. They still have fights and disagreements, the old dynamic is still there, but now it's within the context of a real relationship, to the extent that one can exist within a show like Spongebob Squarepants of course. I love them together!
I also really like the visual changes they made to her model! Just adding bendy metal arms to her portable wheelbase/bendy metal tube/monitor body was the perfect touch to give her a ton more agency and expressiveness while still keeping her design distinctive, unique, and charming. I love how it allows her to wear some human-style clothes, that looks so awesome and cute, and clothes fall on her in a way that I think is interesting because it's similar to but distinctly different from a human. I also really like her expressions. The easy route would have been to just give her a face, but instead they employ a wide variety of things she displays to convey different facial expressions. Sometimes they just modify the shape of the oscilloscope line she has in a neutral state to covey a different emotion, sometimes she makes a face out of ASCII, sometimes she displays a big symbol, and rarely you'll get something like a low-resolution face. It's so visually interesting.