People sometimes scoff at computing languages as old as Fortran, but they should realize Fortran has remained relevant because it's still really good at what it does. It's syntax for mathematical operations is head and shoulders above most more recent languages. It's fast and offers great control of the hardware too. Even today, if you want to write a numerical simulation that's heavy on the math and hard on the hardware, Fortran should be considered.

Everyone who has used it also has horror stories though. It is a very old language and sometimes artifacts pop up. One time I was parallelizing some older code and ran into an infuriating bug where it seemed like some boundary conditions just weren't being passed properly. There were no compiler errors or warnings. Some MPI commands were simply being ignored, but not others. It turned out that the jank-ass compiler I was using for the project had decided to go into Fortran-77 mode (without saying anything) and stripped them out in the precompiling stage (without saying anything) if they were longer than the 72 character limit that Fortran-77 had. I was coding on a computer new enough to have no CD or DVD drive, but was running into the character limit of a 60's punch card system without knowing it!