Personally in my experience
The good:
All-metal, solid, mechanical machine;
vertical shutter (hence 1/125 synchronization speed);
Mirror lock-up (not sure if with all models, but at least with Ft and Ftn);
Possibility to acquire a body that will use Nikkor lenses for dirt-cheap. And most Nikomats will work with non-AI lenses as well either wide-open, or with stop-down metering;
The bad:
Viewfinder is a wee bit dimmer than on Olympus OM-1/2 (or maybe I'm just used to what I prefer overall as a camera);
750-790 grams for body-only is less than ideal for me;
Like most of late-60, early-70's cameras, it utilizes a mercury cell. It may, or may not be a problem. Depends on whether you use "sunny 16", replacement battery, or battery mod;
"Nikomat"/"Nikkormat". Call me stupid, but to me it was the biggest annoyance. I want Nikon to have an inscription of "Nikon", not Nik-something.
EDIT: Please disregard the battery part, FT-2 was upgraded to use 1.5 Volt batteries.