I have recently completed the Hawaii chapter in a compendium on the eminent domain laws of each of the fifty states entitled (not surprisingly): Law and Procedure of Eminent Domain in the 50 States.
Each chapter of this publication is devoted to a summary of a single state's eminent domain laws, and provides the basic tools for understanding each jurisdiction's condemnation law, including who has the power to take, sources for condemnation authority, the rules of just compensation, and the procedural aspects of eminent domain litigation.
The compendium is sponsored and published by the ABA Section on Litigation (Committee on Condemnation, Zoning and Land Use).
The individual state chapters, mine included, are posted for download for ABA members here.