Is it worth buying newer editions of GMAT books....help

Personally, I don’t think Kaplan is a waste of time. I do not believe their tests are indicative of what you will face on the actual exam, but I believe that if you work through their math workbook you will have a strong grasp on the foundations you’ll need to approach GMAT problems. However, you must incorporate the Official Guides into your prep. No test company has really succeeded in mimicking GMAT test questions, IMHO. Personally, I’m not a huge fan of Manhattan GMAT guides. I believe their guides are geared towards those who just need to brush up. I don’t understand why they don’t just release one book and combine all the sections. That seems odd to me (I almost venture to think it’s because they can charge more by separating the books, but I’m trying to refrain from making any erroneous claims). Which book do you start with? There’s no logical sequence. If you just need help in just one or two areas, that’s fine, but if you struggle in quant, that isn’t much help. Second, they gloss over a lot of the building blocks and they overlap a lot of concepts. Kaplan is a lot more thorough in this regard. There is a logical sequence and each chapter builds off the last one. So it just depends, if you need help in just one or two areas, go with Manhattan GMAT. If you need help with everything, I recommend working through your Kaplan book. To answer the original question, no I don’t think they have changed that much.

I don't know what forum you're reading, dude, but I've read very few posts so far where people say Kaplan and PR are garbage. I'm not personally a fan of Kaplan because I don't think their CATs are realistic, but they're still good practice (just ignore the scores and don't get caught up on verbal). I used Cracking the GMAT (PR's book) and it was a huge help. The tests were a lot like the real thing. I would definitely recommend it along with OG 11 and GMATPrep.

To the OP...if you have the 2005 or 2006 editions, that's probably ok. PR's most recent editions come with a DVD, which I got a lot out of. It has some very useful interactive lessons and tools and is cheap enough on Amazon that it might be worth getting anyway.