http://www.colourfulstitches.com/xca...2&bestseller=Y
You know, everyone has a different comfort level.
Looking at the ruler, is it possible to do the same thing with a regular square ruler already in your collection?
Sure.
Do you get all flustered using it?
Is math not your strong suit?
Do you collect rulers that have one purpose?
Do you have $18 you can/want to play with?
If you're unsure about making the Pineapple block, and you can't find the information you want online, then, sure, go ahead and get the book. You might want to check it out first before buying the ruler.
I recently saw Eleanor Burns had a ruler to help with cutting out the strips for a Lone Star quilt. It, like, the Pineapple block, has certain issues one needs to be aware of to successfully complete the block. The ruler was over $60.
I have no need for the ruler. But I'm sure there are people that it will help when making their quilt, and are willing to shell out the money even though they can do the same thing with their standard long ruler. Different strokes.
So that was my non-specific answer for you. Not very helpful, was it? :-D