Would you say this movie is also very deep and extremely intelligent?

From what I recollect, yes. I would say that it's a well-made film, a great piece of art, and to that extent it is intellectually stimulating and/or "deep". It has been some time since I've seen it, however, and have more recently read the book.

The book was outstanding and Kubrick stuck to most of the book when writing the screenplay. To me the movie ended up being a great art piece, along with super acting on a relatively low budget.

At that time in his life, Kubrick could make something great out of virtually nothing, which is why he's a legendary director.

The fact that it’s so memorable shows this as well.