Respect your elders.
The photography gear market is ever evolving. There's something new to buy everyday, and it's very easy to be swept into the mindset that buying the newest equipment will make your pictures better. What a shame this is.
I started photography with a Canon SLR from the 1970s. That camera was built like a tank. All metal design. The camera was made to be used an abused by photographers for potentially decades (4 decades in this case). Things have changed, and most new cameras and lenses are made primarily of plastic. Since photographers tend to upgrade their gear more often in the digital era, compromises have been made in build quality and materials. In fact, to purchase a new, entirely metal bodied DSLR from Canon or Nikon will cost you around $2,000 minimum. That's not to say that just because something is made of metal means it is any more reliable, or robust than something made of plastic. It is simply a feeling of quality. When one is spending hundreds or thousands of dollars on a product they want it to feel like they got what they paid for. Lots of modern lenses (and cameras) simply don't feel as sturdy, and well crafted, compared to their grand-lenses of yesteryear
Optics, Build, and Price: The Nikon 85mm 1.4 D is a testament to the quality of older equipment. This lens was first manufactured over 20 years ago, and yet, It's optics are surprisingly sharp, even wide open. Which is not a given, even for modern equipment. The price is right too, I picked up a used copy for right around $700. That might sound like a lot, but consider the modern equivalent costs around $1700. Nearly 2.5X the price, but you won't get 2.5X better pictures. The D is made of I'd say, 95% metal and glass (the new $1700 model uses a plastic body). The D also has less distortion than the newer model, lines are incredibly straight right out of the camera.
Autofocus: AF is fast and confident. Maybe it's not as fast as the new model, and certainly not as quiet, but I have no problem using this lens in a quiet wedding ceremony environment. Note that this lens does not have a built-in focus motor so it won't autofocus on cheaper Nikon DSLRs. It's hard to achieve sharp focus with any 1.4 prime, but I'd say the D does a better job at 1.4 than my 50mm 1.8G AF-S (a modern prime) does at 1.8, most of the time. Manual focus is better feeling too, although it doesn't have MF-AF override like modern Nikkors do. Manually focusing at 1.4 isn't all that useful to me anyway, however, it's worth a mention for DSLR filmmakers. I've had this lens for almost a year, and it hasn't given me any problems. Even after being nearly drenched in a rain shower, and banged around quite a bit, this thing just kept on ticking.
Chromatic Aberration: This lens can exhibit lots of purple and green fringing when shot wide open. Keep in mind the lens was originally developed to be used on film, in which case CA was not a problem, so it's totally forgivable. On the plus side, CA is relatively easy to control since it appears most often with heavily backlit, contrasting subjects. Luckily, it can also be easily corrected for in processing with Lightroom. There are no fancy nano-coatings or aspherical elements here. Stopping the aperture down helps too, but I usually like to keep this lens below 2.8, so it's just something I have to deal with.
Flare: Actually flare isn't terrible, and maybe if I had a lens hood I wouldn't see it as much, but it can be an issue. Be careful to avoid shooting into the sun or large harsh light sources, use your hand as a shade, and you'll probably be fine. This is one area where modern lenses with fantastic coatings can definitely out-perform vintage gear. And hey, If you want to go all J.J. Abrams on everyone, this lens could be your best friend.
Weight: I would actually put this in the pro category, but all that metal and glass is a bit hefty. Personally I think it adds to the feeling of quality of the lens, and it helps to balance out the weight of the camera body. It's certainly a lot smaller and lighter than a 70-200 2.8, plus it gives you an extra 2 stops of light when you need it compared to the 70-200. Which brings us to our next point...
Prime: No zoom here, it's all done with your feet. What you gain in light gathering ability, you lose in versatility. Having the slightly wider angle and long reach of the 70-200 definitely comes in handy once in awhile. I could probably shoot an entire wedding with the 85, but having the 70-200 in my bag is a very warm security blanket.
Close Focus: This is fact of life with all 85mm primes. Close focus is 3 feet, by no means a macro lens (however it does work nicely with extension tubes). If you're into close focus, look elsewhere.
This lens undoubtedly spends the most time on my camera out of any that I have in my bag (including my 70-200 2.8 and 50mm 1.8). I love the size, feel, and oh yeah, THE BOKEH, this lens produces in my shots. I am a bokeh freak, so this lens quickly became my best friend from the moment I took it out of the box. The out of focus areas are absolutely beautiful and creamy, and I don't have to zoom way out to get that background focus fall-off, like I do with my 70-200. Now keep in mind you won't get the same compression you'd get with a longer telephoto, so the 85mm is not a one size fits all lens for all situations and subjects. In the end, it comes down to your needs as a photographer, but if you're at all into portraiture you should definitely give an 85 a look, and not just this model. An 85mm 1.8D will get you 95% of what this lens does for much less cash. Canon has some amazing 85mm options too, with their 1.8 and the spectacular 1.2L model.
Don't be afraid to try out older gear. Of course read reviews, and buy from reputable vendors like KEH.com (that's where I got mine), but if you do your research you can get great deals on fantastic older gear.