I know this is an old thread, but I have to correct the previous poster – the FG does indeed have TTL, Off-The-Film (OTF) flash metering, and was only the second Nikon body to sport such a feature, back in 1982. It was also the first with a fully automatic Program mode (as well as Aperture Priority and Manual modes). The same OTF sensor used for the flash also provides instantaneous stopped-down metering in the two automatic modes, so if the light changes in the split second after you hit the button it will adjust the exposure accordingly. In short, for its age, this is quite a sophisticated little camera!
The FG is also severely underrated and largely forgotten by many, which is a shame (unless you’re trying to pick one up on eBay). This is probably down to the fact that Nikon aimed this camera at consumers rather than pro’s, and used some plastic in its construction to keep the weight and cost down, so camera snobs have been discounting it ever since. In reality this is still a very sturdy camera, with a durable metal skin over a polycarbonate top and bottom, wrapped around a strong alloy chassis with a steel lens mount – all considerably more solid than many of the more recent cameras Nikon (and others) have produced.
I’ve had one since it was bought used in 1991 and it’s never let me down – I just recently dusted it down after a prolonged spell of disuse, cleaned out and replaced the light seals, and its now up and shooting again in 2011. For me it’s a great size and weight, and also a nice balance of the mechanical and the modern – it relies on only two watch batteries, and although these are needed for the two automatic modes and most of the quartz-controlled manual speeds, the shutter still fires mechanically on the Bulb and “M90” (90th of a second) settings. Combined with manual focus and wind-on, it’ll carry on shooting for as long as you’ve got film.
The FG was a big update on the EM body (adding TTL flash and OTF metering, LED light meter, Program mode and Manual speeds). Oddly it was subsequently replaced by the similarly named and styled FG20, which actually downgraded features (removing the OTF sensor, TTL flash and Program mode again) leaving a camera which was quite a bit less special than its predecessor. I wonder if some of the confusion over the FG stems from that.