I recently returned from Istanbul and used Backpacker for my transit from IST to the Hilton Istanbul based on recommendations here on FT and on turkeytravelplanner.com.

Unfortunately, I had quite a poor experience and poor follow up customer service. The full experience is linked below as part of my larger trip report:

Getting from IST to the Hilton Istanbul

While I believe they can provide a higher level of service as many people have experienced, I certainly did not receive it. I would just like to warn others about the possibility of poor service and to be on the lookout and possibly consider other options for airport transfer.