All cases of depression are, of course, different, but I think this is a great representation of how someone could experience a depression. 
Depressing read and I felt for the character, but I couldn't connect with the character enough that I was devastated for him. I would not describe this as a 'must-read'. I also didn't have the feeling I needed to pick up this book again and I often forget about this book, so I read it over a longer time period, since I got bored.