However, I gather that the sequels go in very different directions. Should I read them?

I read them in high school, but I loved the first three. [edit] By this I mean The Gunslinger plus the first two sequels, The Drawing of the Three and The Waste Lands. I missed Wizard and Glass and by the time Wolves of the Calla came out, I had lost track of the series and nothing I heard thereafter about the last three books in it made me want to go back.