I've used Kreyszig's Advanced Engineering Mathematics in two classes, one a course on Laplace and Fourier series and transforms, the other a course on complex analysis and advanced vector calculus for engineers. The book has straightforward, easy to follow exposition, clear examples, and an appropriate amount of detail (important results are proved, but without the full rigor one would get in a complex analysis course for mathematicians.) The book would be five stars save for the occasional error in the problem sets and answers in the back - they are not frequent enough to ruin the book, but the happen often enough to warrant double checking "strange" results with the instructor. All in all, it is more than adequate for learning the portions we have covered.