Suppose that you have some background in classical first-order logic, and want to learn something about modal logic (including quantified modal logic) and, relatedly, about Kripke semantics for intuitionistic logic. Then the second half of Sider’s Logic for Philosophy certainly aims to cover the ground, and it will tell you about formal theories of counterfactuals too. How well does it succeed, especially if you skip the first half of the book and dive straight in, starting with Ch. 6?
These later chapters in fact seem to me to work fairly well (assuming a logic-competent reader). Compared with the early chapters with their inconsistent levels of coverage and sophistication, the discussion here develops more systematically and at a reasonably steady level of exposition. There is a lot of (acknowledged) straight borrowing from Hughes and Cresswell, and student readers would probably do best by supplementing Sider with a parallel reading of that approachable classic text. But if you want a pretty clear explanation of Kripke semantics together with an axiomatic presentation of some standard modal propositional systems, and want to learn e.g. how to search systematically for countermodels, Sider’s treatment could well work as a basis. And then the later treatments of quantified modal logic (and some of the conceptual issues they raise) are also lucid and tolerably approachable.
This is a game of two halves then. Before the interval, Logic for Philosophy is pretty scrappy and I wouldn’t recommend it. After the interval, when Sider plays through some standard modal logics, things look up. I wouldn’t have him at the top of the league for modality-for-philosophers (see the current version of the Guide for preferred recommendations); but Sider’s book-within-a-book turns in a respectable performance.