So, a few things (aside from the whole nomenclature argument already in another reply)

1. Stepanov's generic programming is a good idea. Every language you've seen with "generics" that's his idea, to the extent "The STL" is generic programming, everybody agreed it's a good idea.

2. But the STL is very old now, so while the idea is good, this is one of the oldest (Stepanov had tried this in other languages before C++) implementations and so other implementations are often better, because they've learned from experience

3. As well as pretty good generic algorithms, the STL also provides a lot of container types (what Rust would call collection types) and these vary not between "excellent" and "mediocre" but between "mediocre" and "inexplicably terrifying". The most charitable explanation is that they're just intended for teaching. If you teach DS&A to a Computer Science class you want the Extrusive Doubly Linked List to teach in class. If you write software you almost certainly never need this type, but it's front an centre in the C++ STL.

There's a single "I guess I would use this" container type, std::vector. It has an insane special case for bool, because WG21 are idiots, but it's otherwise a good enough growable array type and it's not worth building your own instead given the constraints.

Everything else is silly, or bad, or both. std::unordered_map feels like a hash table I made in class in the mid 1990s, but it's actually the provided standard hash table container in C++ 11 onwards. std::list is just that extrusive linked list for some insane reason. The Microsoft standard library maintainer STL could not offer me any justification for what std::deque is actually supposed to be for.

It has some very useful principles, but also some super-annoying gaffes and mis-design aspects. One example: Allocators. What a mess! Or the fact that if a map lookup fails, an exception is thrown. I can't count the times I've had some app just bail out on me with an at() exception, because the author neglected to handle it (and the map/unordered map interface did not force them to). That does not detract from Stepanov's important work.

Nowadays also used by many of us (wrongly) to refer to the overall C++ standard library, instead of what was inherited from C.