Revelation is a difficult book to read, but Wilmshurst's commentary is a useful interpretation of Revelation that is easy to read. It contains many helpful illustrations to aid understanding and make things relevant for today. For a more complex interpretaion of Revelation you might try the Bible Speaks Today (BST) commentary, but this one takes a different stance and comes to a different conclusion. I found it useful reading the two together. This is much the easier read, whilst the BST commentary deals with the issues in greater depth.