To make it short, it was great, I really loved Istanbul and I hope I'll have the opportunity to go there again.
Now let's start the long version.
On the way to Istanbul I spent one day in Bergamo (Italy). It's a nice city in the mountains and I could easily have a walk in the hills, they also have a nice natural sciences museum (free entrance, photos allowed). I did not visit the modern art gallery as I arrived in the middle of the very long lunch break and I did not want to wait for 1h30 (I tried but was falling asleep as I had not slept the night before).
Then on Friday I arrived in Istanbul and easily found a bus which was going to a Metro station, but then I faced a nice trick. I was at a station called "4. Levent" and I din't know that "4." was part of the name and that another station was called "Levent" but after some time Elcin understood the issue and found me :) I spent a nice Week End with her and her fiance visiting Istanbul and tasting local food!
On Sunday evening I joined Elvin and Tuçe on the asian side and we went to a very nice bar there. On monday morning we reached the University by boat, it's nice to enjoy a tea during transportation :)
Monday was really quiet with not much talks (I only attended "Distributed Version Control System BoF" and "Evolution Memory and Disk Summary") but that gave time to talk with people (mostly with Luis and Christian). Then another friend of Elvin joined us and we went for dinner, and then we joined everyone for the first party. We were supposed to only have the first beer free but thanks to people who did not come and the ones who had additional tickets, I think I only paid 2 beers until we left at 3am. We finished the night at a narguile and then I could check in at my hotel at 7am and sleep for a few hours.
On Tuesday I only attended OpenMoko talk and was quite disappointed (I was expecting something more technical, I don't need someone to convince me to buy one). Dinner and bar again, I did not regret having my hotel in Taksim where we ended up most of the nights :)
On Wednesday the GUADEC really started with a lot of good talks (Clutter is getting better and better, Leisa Reichelt's keynote was great, GEGL seems to get ready for use and Christopher Blizzard also did an impressive keynote). We could then seat on the nice "chairs" in front of the university to eat something and wait for the nice party to start on the roof. After that, Taksim again !
On Thursday, there was the GTK talk with the announce of GTK 3, followed by the announce about GNOME 3 by the release team. The webkit keynote was also great, it was actually quite fun to compare the demos in the webkit keynote with the ones in the mozilla keynote the day before. Once again blue chairs to wait for the great Collabora party on the boat. Then, again, Taksim :)
Friday was the closing day but I was too tired and missed the talks in the morning (I was interested by "Measuring the GNOME footprint"), so I only attended the lightning talks, GNOME Foundation meeting, Federico's keynote and the closing. After dinner we managed to find the place for the Google sponsored party which was very disappointing (they rented a club which was probably very expensive, with a DJ working hard to ensure that we can't talk and gave us 3 coupons for the cheap beer in paper cups, all the other drinks being very expensive). Thanks to that party, I went back to my hotel before midnight for the first time!
Having slept 8 hours, i was totally awake for "Evolution: The road ahead" on Saturday :) In the afternoon I left early to visit the city and then Taksim, and Electronica festival. Sunday and Monday where really quiet :)
As I said in the beginning I really like Istanbul and that week. Thanks to all the people who organized the GUADEC and the parties and to my local guides :)
Among the things I enjoyed, I can list the fresh orange juice (made manually in front of you) for 0.5 euros, the cheap tea and tea gardens, the city being very busy but people taking time to talk even if you don't want to buy anything, the overall relaxed atmosphere... The bad thing is transportation but taxis are cheap :)