Stephen King

[Jinsai]

The Gunslinger was written when King was really young. The writing style and pacing change dramatically with The Drawing of the Three.

[Leman Russ]

The Gunslinger was written when King was really young. The writing style and pacing change dramatically with The Drawing of the Three.

I couldn't have said it better myself. It almost seems like parts I & VII were written by different authors, that's how different the styles are. You just have to remember the series has been written over decades