The book is literally legit. It's not a diary, even though the title is 'DIARY', it's a journal.
Believe me, you're going to love this book (and Greg, in particular). I like him the moment I read the very first paragraph of the book and I like his doodles too. He perfectly pictured the important elements on his doodles and you're going to need someone like him in your life because I do.
He has this out of the box sense of humour and it seemed like Greg is trapped in a middle school with a bunch of (he said this one) morons that we can related too.