Hi Ed. Congrats on the 660, thanks for sharing your ESR, and good luck at cracking 700! You will be happy to hear that you could have done much better with some very slight improvements.
Your Quant score is solid, although there is of course still some room for improvement. The main problem I can see is in your Verbal score, where you have significant potential for improvement. As you can see from your ESR, you only got 7 questions wrong out of the 30 counted questions, which is a large percentage of questions correct (77%). Unfortunately, you weren't able to capitalize on this high percentage correct because you struggled a bit on the critical first quarter of questions (only 5 out of 8 correct), lowering your difficulty level somewhat for the rest of the test, which had an adverse impact on your overall score of V34 (71%). Check out
this page for some examples of how you can manage to score in the 40s on Verbal.
1st quarter: 5/8 = 62% correct (after this, the GMAT started serving you easier questions)
2nd quarter: 7/7 = 100% correct (nice job, but the questions had lowered a bit in difficulty so this didn't help as much as you might think)
3rd quarter: 5/7 = 71% correct (still solid, but the questions are starting to get a bit harder again)
At this point, you would have had to "run the table" in order to salvage a high verbal score.4th quarter: 6/8 = 75% (still good, but the 1st quarter of questions ultimately did you in)
The good news is that you have the most room for improvement in the Sentence Correction and Critical Reasoning sub-sections, which are the easiest areas to improve. I recently took a private student with similar score splits from 680 to 770, for example, simply by focusing exclusively on SC and CR.

-Brian
First of all I want to thank you for taking your time in answering me. I agree with your assessment, the ESR just confirms what my feelings were after the exam, that I rushed a lot at the beginning of the verbal section. One thing that concerns me according to your opinion, since I never really got difficult questions on the following quarters because of the earlier mistakes, could it be that my weighted percentile in RC is even lower if I had tougher questions and therefore failed more than I really did?
I will look at the link you send me tomorrow, I will consider adopting that strategy if I find it suitable for me hehehe