In my opinion, reading literature is not always pleasurable. There are times when literature makes demands of us.
A question such as this one is rooted in opinion. Everyone will have a different approach to answering it. I think that there are times when reading literature is extremely difficult. Sometimes, literature is very sad. When reading Flaubert's Madame Bovary, there is not a feeling of a "tasty meal" or "a hot bath." It makes a severe demand of us to examine life in the Realist mode that Flaubert has painstakingly created. To see the plight of characters like Charles or Emma is draining. Absorbing this painful and nuanced condition is not always pleasurable.
There are times when literature insists that the reader take stock of the world and their place in it. In many cases, it is impossible to escape this demand. When Beckett presents us with his characters in Waiting for Godot, he demands that we place ourselves in the same position. Would we wait for the dinner guest who does not arrive? Beckett uses literature to insist that we identify what is important to us and assess how it impacts our identity. This is another example of how literature is not necessarily pleasurable. There are times when literature forces us to ask difficult and uncomfortable questions about who we are and what we do.