It is probably the sign of a good professor that they are producing their own course material rather than just telling students to go and read a certain text book chapter.
That material is what they think is important and is in their own style, if that style clicks with you then great, if not then you're out of luck.
With text books, you get everything, not just what someone thinks is important and you can go to the library and find one with the right style to suit you.
I still have all my text books, and I actually do use some of them occasionally if I need to revise some topic.
The maths department where I attended did this for first year material. They put together a ~100 ish page packet that we paid something nominal for, making all other textbooks optional.
So who sets the question paper and homework assignments? If it is the same prof who hand over the material, that's not a very good class. I wonder which subject this might work well for.
It works well for courses which are based on critical reasoning such as physics and mathematics. Going both with and without textbooks for many courses I can say that the textbook doesn't make much difference if the notes from the course are done well. If they aren't then the class can be a real pain.
After studying for a semester in Canada with textbooks, I did not see any added benefit to using textbooks.