I have never had a 50mm Nikon prime, but I bought the 55mm (non AF) because I thought it could serve both as a normal lens and a macro. I used it to document stuff for work for about 15 years. As a short macro it is superb. As a normal lens I found it rather disappointing: not sharp and (obviously) not terribly fast either. A practical irritation is that the front element is very difficult to clean (because it is so deeply recessed). Of course that also means it doesn't ordinarily need a lens hood, but then again you have no choice but to add filters in front of that deep hood, and you need an extra hood to shield the filters.... I'm afraid that lens contributed to me moving from Nikon to Leica, something I shall never regret.