[.uk] Introduction to Mathematical Finance: Discrete Time Models (ISBN 1557869456)

Clear & concise:
Pliska's book lays out the fundamentals of discrete time models in a clear and concise manner. The book is mostly self contained and well supported with examples that enhance understanding. I read it as a part of my introductory Phd finance course along with Theory of Financial Decision Making by Ingersoll and Foundations for Financial Economics Huang & Litzenberger (not direct competitors) and found Pliska's book to be the most understandable of the three.

Unreadable:
Pliska may be a genius, however this book is not an "introduction" to anything. It is very information dense and incredibly difficult to follow on a undergrad level. Expect lots of theorems, equations, badly laid-out text and formulae - very little practical application and common sense explanation of what he's trying to do.