For anyone who is using plain good old C/C++, WTL/STL/ATL are a boon to work with. They are much less complicated to work with than MFC, make smaller executables, robust code and the best thing is they can help create better (read modern) user interfaces much easily than MFC.
But there are down sides too. You will not find a proper documentation for the same. No books exist for these three. Even if there are, they are hard to find. And MFC covers a much wider range of classes/controls than these.
And if you come from a MFC background, believe me porting to WTL/STL/ATL will not be less than a nightmare.
But why you want to use them anyway? Any special purpose?
It all depends on what sort of project you want to use them with.
For me, I only use VC++ with MFC, or now, my current favourite, C#. Nothing beats it.
