Granted obatining your CPF isn't going to make or break your career or send folks to your shop in droves... it's a great personal experience. The library of books used for studying are so interesting and make great reference guides. Even if you never challange yourself by taking the exam, the library is a must have. If you love framing, you'll love reading the books... and you WILL learn many things you did not already know. Not only will you read things you already know, you'll actually learn WHY you've been doing them that way, and not just because "that's the way you were taught". Besides, there is more than one way to do many things, and just learning different variations of certain techniques opens many doors to different ideas.
Don't listen to CPF bashers... it's about the knowledge you obtain reading the books and not so much about the title.
-Erin "Proud to be a CPF"