I have been playing guitar for 25 years and studying theory more than 15 years. Unless you are a professional musician or music theorician, you would not want to dwell into music theory so much, that sometimes; it can be very hard to find an answer even to an easy question.
ie; it took my years to find why i need to use some special chords, why i have to use some out of key notes in particular scales/progressions etc. Somehow this book answers those kind of questions too.
When i saw that some of such answers are even in the early chapters and very simply explained, I hate myself not reading this book before the other dozens of music theory books i had read. Mr.Rooksby knows how to simplify things and make small bits to chew.
And about the melody writing,
As author himself mentions too, you can not write a great melody just reading a book. You need an initial inspiration. The theory is then needed for perfecting that inspiration. What this book gives is that theory.
Although book has several chapters, it progresses like exercise 1, ex.2 .... So you can progress page by page or jump to any chapter you need. I recommend you to read from start to finish.
Book starts with the very very basic example. Choose your key, play one of the notes from that key four times in every bar, hormonize it with the chord that has the same name with the note you use in that bar (not exactly in these words of course). In next exercise, exactly the same notes with a small variation; change one of the four notes in the bars with another note of the key. etc. etc. Yes, it does not sound creative so far.
After going through all exercises, you end up with the same backbone but definetely much better piece. The difference (at least the concept) is like, nursery ryme twinkle, twinkle little star and Mozarts 12 variations to it.
There are few down sides too.
In exercises, he explains one thing and gives a few examples but not the whole list
ie1; in scales he mentions myxolydian, dorian and gives the notes of this scales but not the other scales.(BTW, by reading his other books, i start to think that he hates, minor scales :=))
ie2; He mentions chord inversions, replacements but not all applicable chords etc. It is not a problem for me but it can be hard for the beginers to find out themselves. I understand that it would be frightening and waste of space to list all when ever they were mentioned. At least there should have been some kind of summary charts at the end of the book for future reference.
As his other books, he refers to some songs which it may be hard for the reader to find.
He keeps refering to bars, saying "look for the variation between bar 8 and 11". But the bars are not numbered that you have to count everytime. Numbering the bars is a small detail but time saving and a good habit of good musicians.
As he already mentioned in the book, the audio CD is not arranged as a regular songs but only includes the melody and the chord/rhythm tracks to allow readers to concentrate on how melody develops. Thats OK. What i did not like about the CD examples are, most of the tracks are created with synth sounds (or at least I hear so). If he was to use real instruments, the differences between the examples would be more pronounced and we could grasp the note/interval/harmony relations better. Besides it would sound less boring.
The examples only play once. For people like me who hates to set their players to shuffle mode or replay mode it becomes annoying to stop the track and rewind to hear twice.
You can not seperate music as melody, harmony, rythmn and lyrics especially when you try to explain the theory behind it. So even though this book concentrates on melody, as i mentioned in the header, it gives quite a lot in other components, too. An the details for melody is satisfactory.
It can be useful for any level of musicians. If you do not have any kind of music theory, start with this one before trying to learn from dedicated theory books. It does not include everthing but it will definely help you understand the dedicated books with ease.