The Istanbul metro is overcrowded, with too few trains in service. If you don't like being in a rat tunnel full of scurrying impatient people, you'll hate the metro.

My room was 23 euros and extremely dilapidated. The first room had a short in the A/C, so I was moved to another room. that was naturally cool enough not to need A/C.

The businessmen of Istanbul are very appreciative of their customers. Other than the metro card vending & top-up racket, I didn't encounter any of the scams or ripoffs that other people claim are prevalent here. Prices were often high, like 110 euros for a kilo of baclava, but clearly posted and honored.