Nice book on a subject taught a lot. Nice easy read. A nice amount of doctrinal information. Not as light a read as Wiersbe's "Be" books but not super hard to understand. I would say good for a 3 or 4 year old in Christ. Mr. Morgan has a lot of his stuff in writing and this is one of his best.
About the Author
G. Campbell Morgan (1863-1945) was a leading Bible expositor in England and the United States. Despite a lack of substantial formal training, Morgan was a prolific writer and teacher. Ordained into the Congregational ministry, he was the pastor of Westminster Chapel, London (1904-17 and 1933-45). Morgan also conducted two very successful teaching tours in the United States, including work with D. L. Moody's ministry.