Can't comment from a working perspective, but Istanbul - as with all of Turkey I've been to - is awesome (and I've lived in a bunch of places). All the exotic of North Africa filled with people who are honest, decent, friendly, and won't harass you. If I get myself mobile again, Turkey is top on my list of places to spend 3-6 months. Did I mention the food is great?
Istanbul is awesome. Scenery is beautiful, and the waterpipe cafes don't mind if you sit there the whole day, as long as you order tea or something every now and then. Quite a lot of them have decent WiFi as well, though many sites are blocked in Turkey.
I haven't been to Berlin but have spent a lot of time in Istanbul.
Istanbul is big, really really big, like mind-bogglingly big. It's Europe's biggest city (although technically part of it is in Asia too) but if you want to live somewhere posh like Bebek or Nisantasi it's as expensive as anywhere else nice in a major European city. If on the other hand you're prepared to live in a less nice area or a bit further out then there's some good deals to be had.
If you're living somewhere properly then the quality of the food is far higher than that accessible to me here in my bit of the UK, eating out is generally more expensive in terms of average income percentage but typically less expensive than London in terms of raw costs.
I would highly recommend Istanbul to anyone looking to try something a bit different. It really does feel like nowhere else in the world, a chaotic mishmash of east and west but with a great vibe and great people.
If any of you guys need help / advice on just about anything in the city, let me know. I'm a Turkish expat designer (from Istanbul) living in New York—I wouldn't mind helping a fellow HNer.
I don't remember the rent exactly. It may have been somewhat similar or slightly more expensive in Istanbul. But eating out is definitely more expensive there, unless you want to subsist on lahmacun.
It depends on what you eat, but there's far more than lahmacun on the diet. Now, you're probably sticking to Turkish food (Chinese is going to start at 15TL, the equivalent of 8.5 dollars or so) but I'm regularly eating decent food for the 3-8 dollar (2.5-6 euro) range, with drink.
Great produce is also ridiculously cheap here, which makes cooking a much better deal.
