the Classic Pan 400 (= Fortepan 400) are indeed "classic" film from Hungary, quite different from modern emulsions. Seems like a lot of Germans over here have experience with it, here's a summary:
- Famous for it's grain. Seems like fans of that kind of grain do like the film.
- Classic look, good midtones.
- Sharpness okay
- Exposing the 400 at ~ 200 ASA not a bad idea.
- Classic Pan is more like a tungsten, not a daylight film, with it's expanded red sensibility.
- D76 / ID11 seem to deal quite well with it.
General problem: The manufacturer does not have quality control comparable to, say, Ilford. The film can behave quite differently depending when and where you got it. People here call it a film for enthusiasts, but most users are disappointed by it and discontinued using it. Personally I only used it for a few rolls, long time ago, in 35mm. The results were horrible, but that of course was also due to the small neg size.