I have been a staunch Constant Reader for far too long to give anything but a biased review of the beginning of the genre bending Dark Tower series. Actually, not so much a review as a fan's recommendation.
The first time I read this, I was 13 and firmly planted in the mythical land of black and white; heroes behaved a certain way, as did villains. In that perspective, Roland had the appearance of a good guy, but made the decisions of a bad guy. I hated him the first time I read this. My attitude towards Roland has changed, from reading the rest of the series as much as from life experience.
Jake, however, I loved from the beginning...and love all his incarnations through out SK's works. In The Gunslinger, my heart went out to him. Jake saw the good in Roland, innocently believing Ronald's better nature would be making the decisions...only to be crushed, again, by the wheel of ka.
The Man in Black is significantly more interesting when not interacted with too much. Here, he is mysterious and powerful. Later, not so much. He is a despicable man who deserves all that happens, and more.
After reading the entire series, this beginning is ever so much better. Seeing Roland begin to love Jake, seeing the steely strength Jake possessed so young and after having been though such strange things. I love Roland and he has a permanent place in my heart, flaws and all. There's no such thing as a black and white world. Good guys can be selfish and do make bad decisions. Sometimes bad guys show mercy or even love.
Hayao Miyazaki's films are wonderful examples of this truth.
The Gunslinger, while a pretty good stand alone story, is also a worthwhile introduction to the mythos of the SK universe. As a 20+ year Constant Reader, I recommend it.