Although Fortran compilers may produce fast code (they have to - there's no chance to play with SIMD intrinsics or templates unless you want to use C++), I don't find them very good. I've personally hit several bugs in gfortran. The code I maintain now has some extremely ugly hacks to work around unfixed compiler bugs. I recently tried compiling it with Intel Fortran and got a compiler crash on one input file. Maybe they work well with Fortran 77 level code, but the Fortran 2003 level support seemed rather buggy. I suppose this is the problem with a minority language.

I won't recommend Fortran unless the code has to be written by scientists who know nothing else. It has horrible string support, no data structure or algorithm library (like STL), no templates, few non-numeric libraries (e.g. http, json...) and (as above) buggy compilers. Furthermore, C++ gives you much more control over numerical speed when you need it.