Oh, I felt so much like 15/20 years ago! I remember falling in love for the first time with a guy who turned out to be a complete idiot and looking for all those "signs". Many of the situations described in this book are very similar to the ones I experienced.
Mit Jakob würde alles anders is a really funny book most of the time. But I also liked the sader parts, especially Gussi's. I often felt very sorry for him. The ending was very satisfying too: not all the story lines had a happy ending but I finished reading with a smile.