I had the 50/1.8D. I bought it because i loved Nikon bodies, even though i've long been a Canon user. I got the 1.8D because i had seen a few image samples with really nice bokeh.
I shot the D with some Plus-X and was very encouraged. It's sharp, lightweight, and cheap.
Later, i shot it with some fine grained color neg film, and got more typical bokeh results. Typical, meaning BAD. It may perform well at a few apertures, in ideal circumstances, and/or with grainy film that breaks up the out of focus shapes, but in no way could i depend on the D lens to do what i wanted. After those last results, i quickly sold it.
I was waiting for a 50mm Nikkor that could offer more predictable, pleasing OOF rendering. Had to wait until the 1.8G came out. I still don't believe it's in the Canon league, but i'm not preoccupied with it now.
So, re: your question.... Depends on what you want to shoot and how. If bokeh is a component of your pictures, skip it. $50 is cheap for a lens, but it's expensive considering the 'damage' it can do to your film.
I would suggest trying the 50/1.8G. From all the tests/reviews i've seen, it offers both the best bokeh of the 50mm Nikkors (not including the Sigma 50/1.4), and also top level sharpness.
Take a look at this:
http://nikonrumors.com/2011/11/03/s...r-nikon-f-mount-compared-by-cary-jordan.aspx/
I don't know who this fellow is, but the conclusions/results sorta jive with everything else i've seen.
I like the 50/1.8G's build. It's larger than the D, but looks and feels perfect on my F100. It's very lightweight. It feels perfectly balanced on the camera, but when you have it off the camera, in hand, it's surprising how light it is.
re: the 50/1.2 AIS.... I've owned this lens on two separate occasions. I don't remember why i sold it the first time. The second time, it was probably also because of inconsistent results. Or, at least, results that didn't seem to match its reputation. I really have a feeling these Nikkor 50s tend to sing at certain apertures and be awful at others. And, i tend to like the apertures that don't work well.... I have a 50/1.8 Series E (manual focus), because i LOVED some photos i saw online. I asked the photographer what aperture he shot them at, and now i pretty much stick to 2.8 or smaller with it. I just kind of expect that wider apertures are like rolling dice. Not so with the Canon glass....
Oh, and NO - the G is supposed to be a different formulation than the D.
If it matters, the G focuses pretty much silently. No squeals or whirring.
