I have used — enjoyed, even — lenses from the 1960s and 1970s on my DSLRs and mirrorless bodies in the past decade and a half. Vintage lenses are often cheap, and they only take one adaptor to work with modern mounts. This is a beautiful part of photography, making experimentation more accessible, but there's another way to look at this: Why can I use a 70-year-old lens and the only thing I'm missing is autofocus?
There will be a lot of answers to that question, but perhaps the question won't always make sense. The new Viltrox AF 135mm f/1.8 LAB lens for the Sony E mount has that combination of a long focal length and wide maximum aperture that has been enjoyed since the Pentacon 135mm f/2.8 of the 1970s that has garnered the name "bokeh monster", but it's modern too. It has a full-color display on the barrel, wireless connectivity, and the ability to change the aperture by less than the typical one-third of a stop, among many other features.
The question photographers need to ask themselves is this: do you want more technology packed into your lenses? Or, is the juice just not worth the squeeze?
Given that a similar lens from an OEM would probably cost upwards of $1,500 (if not a lot more), this seems like a steal even without the extra tech. The combo of a longish focal length and that nice big aperture is awesome for $900. I hope Viltrox joins the L-Mount Alliance so I can enjoy this lens some day.
The performance, build quality, and price seems very good. But, dang, the size and weight, though at 2.7 lbs. Almost as girthy and heavy as my Samyang 35-150 f2-f2.8 at 2.9 lbs.
--- "do you want more technology packed into your lenses? Or, is the juice just not worth the squeeze?"
To be fair, this particular lens isn't really squeezing the buyers. With that said, for my use, I don't need all kinds of bells and whistles in a lens. I just want IQ and speed and accuracy, and preferably the lighter the better. If I were in the market for a 135 f1.8, I'd go with the Samyang version. They've been on sale for $759 (regular $799) for least a couple of week now. And, they are lighter and 1.7 lbs.