I just gave my GMAT and am really happy with the score :
GMAT: 780 99%
Q : 50 95%
V: 48 99%
AWA: I had the templates prepared and just stuck to them.
Quant : Got 3-4 hard Prob/P and C questions.I think this is where I screwed up and did not get a 51 in Quant.
The rest of quant was easy, similar to level in Powerprep and GMATPrep.
Verbal : I found this pretty easy, similar to Powerprep and GMATPrep.I got a couple of difficult SCs and 1 difficult CR.
The scratch paper system is not ideal as they only give you a limited amount at a time.I had to get more scratch paper on 3 ocassions.
Just for perspective these were my scores on the practice tests I gave:
GMATPrep2 : 750
Powerprep 1: 780
Powerprep 2 : 780.
As is evident Powerprep is a pretty accuracte predictor of the score.
I only started using GMATclub in the last 2 weeks and have found it to be an excellent resource.