On the plus side, Fortran has more actively developed implementations than any other language. It is critical to some of the most important applications that exist. One can write code in the portable subset of Fortran and extract very high performance from very expensive HPC systems over many generations of processor and systems architecture.
On the down side, advancement of the language has become moribund -- the last major standard was in 2008 and the two revisions since then have been minor. The standards committee creates new features from whole cloth without prototyping them, and without fixing the bugs in the spec when bugs are discovered eventually by implementors. There has been no standard public test suite since F'77, so implementations vary. There are highly portable features that are not standard and there are standard features now that are not portable.
I'm working hard to try to improve this situation on the compiler side.