It lacks networking features which is pretty limiting. I use QT for 90% of projects, this is the new STD for me and I'm quite happy :)

Ah yes I forgot that. I remember Stroustrup explicitly stating that he avoided adding stuff like GUIs to the STL as people forget that C++ isn't just ran on desktops.

I use wxWidgets with a mix of STL (you can tell wxWidgets to use STL for its containers if you want) and all works well.

I had been happily using extra networking libraries and the ease of using libraries means I kind of forget that the STL doesn't have it - I just get into a habit of using the right library for the job, which is the way it should be I suppose.

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/ gives a sense of where the standards committee is going.