The best tour guides are informed, hospitable, and passionate about their work - Salih is all of the above. We were two people and we made our booking at midnight the night before - and Salih accomodated us, even though we were actually the only people on the tour that day. Unlike many guide companies, he doesn't do things just to profit. He runs his business the right way and bends over backwards for his clients - because he is passionate about his work, and about sharing the culture and history of Istanbul with visitors. Our tour ended up being especially small, but he always keeps a size limit, so it will never be more than 11-12 guests anyhow.
Istanbul is a massive, sprawling, maze-like city and the tour helped to make it manageable - a great jumping off point for my time here. I learned a lot about the history and the sites, but I also just enjoyed hanging out and walking around with Salih. Many of the other tours seemed to be far more expensive but I couldn't imagine a better, more personable experience than the one we had (Salih also led us around for way over the amount of time allotted for the tour). My buddy and I did the Secrets of Istanbul tour and will be going back for the Istanbul in Two Continents tour.