The Dark Tower V: Wolves of the Calla is the beginning of the end as Stephen King prepares to wind the story up as tight as he can and then let it all roll out. The story is pretty good, another show of the Gunslinger's code as they stand up for a town against a cyclical terror of its generations while balancing their own goals and problems.
The catch at the end is an interesting one, although I wonder if it has given away too much of what's to come. I suppose the ending of the story could still surprise me, but I've got a few guesses as to what will happen.
During the large battle scene, while somewhat sad as the battle is not won without loses from the "White" side -- there is at least one piece that I about died of laughter. I had begun to suspect that King had borrowed an artifact from another current famous "7-book series", but, I hadn't realized to what extent it was. I wonder what that author thinks of its use in this story. I really need to put up a spoilers page so that I can talk about my ideas for what the end will come to as well as this little tidbit of info.
As noted, the story is good and definitely worth the read, but it is very important to have read the previous 4 books or some of the details of this one will be lost to you.