I am an undergraduate whose trying to go directly for his MBA.
So far the preparation was horrible

Diagnostic: 570
CAT 1: 400 Scaled scores: Q- 22 V-21
CAT 2: 420 Q- 25 V-16
CAT 3: 500 Q- 28 V-22

Ok, I have to say that at the third CAT I concetrated as if it were the real deal. My GMAT is tomorrow so I feel like I will do terrible to miserable.
The other comments make me feel a little bit better but since I did not do as tarrific as the other reviewers I feel panicked.
I would like to score above 550+ and best outcome would be around the 620 areas.
I hope that the other reviewers are right saying that the Kaplan is more difficult than the real deal.
I had only a ten days time to study for the test.

This book together with the official guide from ETS is a must have for an efficient preparation
The exercises from Kaplan are tougher than the real GMAT questions you will get, so don't be desperate if you don't score very high on the 4 practice tests
I scored around 600-630 on all 4 Kaplan practice test CAT's

On the test day I got a 730 ! far above my expectations, before seeing my score I was a bit worried as I felt that the questions I got weren't difficult enough

I had the most absurd experience with this package. I read the entire book and did the practice problems provided in the text. I was feeling pretty confident until I used the CD a few days before the exam. These are the scores I was given:

Diagnostic: 640
CAT 1: 570
CAT 2: 560
CAT 3: 550

That's right... my score kept going down. I was feeling pretty panicked on test day, but I had no time left so I just went in and took the exam. Somehow, my score was a 740.

The CATs on here will be very difficult and most people will get a lot of answers wrong. These tests are ONLY useful if you go back and really take notes on the lessons learned from missing certain questions. Just keep your head in the tests and keep ignoring the ridiculous scores the software gives you. That seems to be what worked for me.

I loved the fact that this book and CD-ROM presented questions that were much harder than the actual test. After looking at reviews it seemed to me that the average score on the Kaplan tests were 10-15% below what everyone was getting on the real test. The CD-ROM was good but needs to be updated to run on more current versions of Windows OS's.

My Kaplan scores:
CAT 1: 480
CAT 2: 510
CAT 3: 510
CAT 4: 550
Powerprep CAT 1: 570
Powerprep CAT 2: 590
Actual GMAT: 630

This book was a big help to me in my preparation for the GMAT. When I was looking for books to buy, I checked the reviews on Amazon and bought this book along with the KAPLAN 800 and Official Guide. Well I ended up having to take the test sooner than expected and so with only 3 weeks to study, I ended up only using the Kaplan book and not the other two. I studied for one hour each day after work and then took the tests on the weekends. I must say that (as was said before by other reviewers) the value of this book is in the CD that comes with it. I only gave it four stars because the CD is not exactly easy to navigate, however it does contain some very useful tests, including the four CAT tests, which are much, much, much harder than the actual GMAT and are very helpful in preparing you to answer tough questions in a short amount of time. Here are the scores I got over the three week period:

PowerPrep Test 1: 640
1st KAPLAN test: 540
2nd KAPLAN test:560
3rd KAPLAN test: 530
PowerPrep Test 2: 710
ACTUAL TEST: 710

Obviously the KAPLAN tests are much harder than the actual test but if your ego can take it, they really pay off. I definitely recommend this book and I know that if I had used the others and studied longer, I could have gotten a higher score as well. Good Luck!