Every time I have to work with text in C++ using stl feels like pulling teeth. It has gotten better over years, but even php gives one stdlib envy.
The idea to base everything on iterators instead of ranges, blowing up the code (and amount of errors) — it would have made sense for pure algorithms, but stl insists on having ownership of object placed in the containers.
No sane way to work with binary data. Inconsistent allocation and exception ideology through the years. Mysteriously missing functionality.
What little ruby, python, php I have written — nothing has felt as clunky as STL.
E.g. vector has no "sort" member function. What great benefit not adding it for convenience has brought?