Jack: A Life of C. S. Lewis
Much more personal than the McGrath biography and with lots of interesting quotes and anecdotes. Each view on Lewis gives a different perspective and I think it's necessary to compare several in order to get a picture of this complex man.
Short Review: A good biography of CS Lewis. The important part of the book is that it is written by a long time friend and former student of Lewis. He was actually there for much of what is being written about. He went with Lewis the first time Lewis met Joy. Lewis regularly visited their home. So this has memories, not just research. No biography is perfect, but if you are reading several biographies about Lewis, this is one that you should probably have on your list.
My full review is on my blog at http://bookwi.se/jack-a-life/