The mCable Gaming Edition HDMI cable from Marseille promises to "eliminate jagged edges and shimmering texture without creating blurring artifacts" among other things. The cable also starts at around $100 for a 3-foot version and after being told and and again , I originally took this claim as pure marketing, but I was wrong.
The mCable is more than just an HDMI cable, so there's a good reason why it's pricier. Inside one end of the cable is a graphics processor (powered by the connected USB cable) that upscales the low-resolution graphics from older or PC games, and the Nintendo Switch. It works with new consoles, too, but since those already have powerful graphics processors, the mCable Gaming's performance is not as noticeable.,
The Switch's native output is 1,280x720 pixels and it can use some help, especially when it's connected to a large full HD or 4K UHD TV. And, as I mentioned at the top, it promises to help with aliasing (aka jaggies) on curved lines and punch up contrast and color in addition to the upscaling. It also does all of this without any discernible lag, which you would typically experience with any post-processing.
The proof is in the pixels
First off, "eliminate jagged edges" is an overstatement. However, while the cable doesn't miraculously create straight lines and smooth curves from jagged edges, the processing does soften them so they appear less severe and it does this without smearing details. What I experienced was definitely in line with the sample images on the company's site.
What I appreciated most about the mCable is that it generally cleans up the image quality without making the overall picture too soft. Along with the reduced jaggies, color and contrast are improved. The results remind me of the Dehaze feature in Adobe Lightroom, which can help create some additional depth to scenes, like the water in the Splatoon 2 shots above.
The mCable works, but how much it works seems to be dependent on the content and the console. For example, with the Switch, Mario Kart 8 and Splatoon 2 did look better. But other titles like Kirby Star Allies and classic titles from the didn't show a marked difference.
Anyway, back to the initial question of worth. If you want a better picture from your Nintendo Switch games without taking a performance hit, the mCable does work. For me, the improvements aren't enough to pay $100 to $150 depending on the length you need. On the other hand, I'm not a serious gamer, which is really who will appreciate what this cable can do.
It's worth mentioning, too, that Marseille's site is currently promoting an upcoming Kickstarter campaign for an adapter called the mClassic. From the looks of it, the adapter is the brains of the mCable, but it's BYO HDMI cable instead of an attached one. It's also apparently been designed by NWA's Arabian Prince, so there's that. The mClassic will be $79 for the Kickstarter campaign, but $99 at retail.