Writing Systems: An Introduction to Their Linguistic Analysis

Coulmas' basic thesis is that writing systems are not a simple method for transcribing speech into text. Rather they are complex cultural systems which allow language to be approached in ways that speech doesn't provide for. This book is clearly written and has lots of examples. You'll have a much richer understanding of any writing system you encounter after reading this book.

One of the most insightful books on the topic. It's not overly ambitious to systematize the evolution and topology of writing, like Gelb. It highlights a number of linguistic principles underlying.