I've tried to make several Foma films work well, but I couldn't. And I use some of their great papers long ago.
Apart from quality control, and apart from the three problems stated by Drew Wiley in post 16 (low speed, low gamma rise, low reciprocity) all leading most of us to wish more from their films and their tone, I feel as if at Foma they talked about ISO in a different way than Kodak and Ilford do: maybe Foma film designers really stretch things and don't tell us, when they print box speeds on their films, they talk about an ISO that reaches higher contrast -at box speed- than best films in the world do.
Anyway, I think Foma100 can be well used (at 25-50 for best tonality depending on light and developers) for tripod photography: in that case, tripod, their peculiar behaviour is a pain only for some scenes and types of light.
But for handheld photography, Foma films are always clearly inferior to Kodak and Ilford films.
In my case, I use ISO400 at EI640 and at EI1000 for soft light, and all ISO400 films by Ilford and Kodak give great tone at those speeds for wet printing, but Foma400 can't do that with best tone and best grain. The difference is huge.
Sometimes Foma400 is the only film available here, because it's the cheapest fast film in the world and it's commonly repackaged for students, so I tried to make it work well just in case, but it was a pain every time I tried. And frames with quality control problems were common all the time, in different recent years.