CALD gives that "as far as sb is concerned" means "in a particular person's opinion," so you may say:
"As far as I am concerned, this book is not only fantastic, it is also very enlightening," what simple means "In my opinion, this book is..."
Dear teachers, is your opinion on this the same? Is there any difference between using "as far as sb is concerned" and "in a particular person's opinion"? Is it just a matter of style?