Are Strategy Guides Worth Buying?

[Spade]

The one guide I recently bought, which IMO was worth every penny was this: 

http://www.amazon.com/Ni-No-Kuni-Wrath-Official/dp/030789598X/ref=sr_1_sc_1?ie=UTF8&qid=1420867853&sr=8-1-spell&keywords=ni+no+kuni+wrath+of+the+white+witch+huide

It's the hardcover edition and let me tell you it's gorgeous. From the cover art to the actual inside. It was also extremely helpful in the familiar guide and what evolves into what, etc. Didn't really need it for the walkthrough, but mostly for the inside art. 

Edit: To answer your question, it's not that practical anymore since the Internet.... There are also so many incredible guides online for games. The most recent one I used was for Persona 4 Golden KADFC's guide and that was one of the best written online guides in completion and overall design.