My background:
30 year old, working full time as a Research Scientist (plus 2 hours a day of commuting time in the dreadful roads of outer London). I am Spanish and learnt English about 6-7 years ago.
My experience:
I started preparing about 6 months ago, but I didn’t study much until about 2 months ago. In the first 4 months I just did the exercises of the Kaplan and Princeton books, and a few from the CDs. I got the OG at the beginning of September and I did all the exercises. My main problems were with data sufficiency, especially the last 70 exercises or so. Also I was slow in some problem solving.
Verbal was OK, I got about 85% correct at the first go at it. I then re-checked the ones I’d missed the first time and got about 80% of these correct. I thought I was prepared for verbal.
During October I finished the rest of Kaplan and Princeton, and did the math from Kaplan 800.
Did some tests:
Kaplan: 640 (Q36, V40), 550 (Q35V30), 600 (Q40,V32) and 560 (Q36, V30)
Princeton: 650(Q37, V43), 690 (Q39, V46), 690 (Q45, V41), 610 (Q42, V33)
PP (after OG): 690 (Q42, V42), 770 (Q50, V47)
In the previous 2 weeks before the exam I practiced a lot of math , but verbal only during a couple of CATs.
I took the GMAT on the 17th of Nov.
AWA was OK. I used it to get into exam mode more than trying to write the best essay of my life as recommended by somebody in this forum.
I started quant quite well. The first 4-5 questions were not difficult and then I got one that I did not understand. I panicked and I lost about 3 minutes. I guessed and moved on. Then I got a mixture of difficult and easy questions throughout. On the difficult ones I guessed in some of them when I though that it was taking too long. I might have guessed about 6-7 times: 4-5 complete guess and 2-3 between two choices. My feeling was that I was doing very badly and expected about a score of about 35.

There were some unfamiliar questions in the math. Not very difficult, but took me some time to understand them. I’ll think of some variations so I can post them in the math forum without getting into trouble with ETS.
Then I started verbal and I was a bit more confident because I thought that it was my strong part of the GMAT. I got a couple of SC, a bit difficult ones, a CR and then two texts with 3-4 questions each. I didn’t find them very difficult. Then a boldface CR and more SCs. During the verbal I was unsure about some choices, but in general I thought I was doing well.
At the end I got my score: 610 (73%ile), Q48 (86%ile)

higher than in any practice, and V27 (46%ile)

lower than in any practice test. I couldn’t understand this.
Later thinking about it I attribute the poor verbal to a lack of practice in the previous 2 weeks and over confidence.
The most strange thing is that the scores reflected the opposite to my feelings during the exam. This worried me.
I think I am prepared to get around 680-690, I just need to focus on the verbal a bit more so I decided to take the GMAT again in December. But the only place to do it in the UK is London and it is completely booked until January. So I’ll have to wait until then. For the whole of the UK I estimate that there are 50-60 places a day to take the GMAT. No surprise that it is so difficult to make an appointment to take it. So, an advice for people in the UK: BOOK EARLY.