The Zap Gun is another Philip K Dick novel bursting with great ideas but flawed by a lack of storyline. Was this book haphazardly written, or haphazardly edited? The premise is masterful, and the ending, which builds directly on the premise, is outstanding. But there's an awful lot of bits of pieces of plot between the two.
It's not that Dick doesn't have enough plot ideas to make it work. Rather, he sets off on lots of plot excursions which don't really go anywhere, and don't contribute to the overall mood or direction of the book.
Despite everything I enjoyed this novel, and I've read it about four times now. The double premise - a toy maker who can't design a toy simple enough to sell, and weapons designers who design in a trance and are unable to design a weapon that works - is intriguing enough, and the eventual resolution is excellent.
I suppose my final comment is - this would have made a great short story, if only Dick had had the self-discipline to cut out the unnecessary.