This is a surreal fantasy. The entire book is a setup for the rest of the series, which I haven't read (yet?). It is an interesting read and should be encourging to all us starting writers. It is also interesting to read the introduction and forward. I haven't read anything else by King except for "On Writing" so can't say if this is his usual quality or not. To me it seemed like a first novel which it was.
The edition I read is a revision of the original written in 1970 and published in parts starting in 1978. For this edition he cleaned it up both logically and stylisticly. It would be interesting to read a first edition it see what changes he made.
I do reccomend reading it if surrealistic fantasy is acceptable to you.