Hi John,
Haven't done it for a couple of years, but if my memory serves me right it was about 2 hours and at the time cost 5 Tl each (probably increased now as all of them), we enjoyed it, I think it depends what time of the day you travel with regards to how full it is, outbound was not a problem, but returning we caught all the school kids going home, but ho hum !. We like using the Dolmus for the economy and to "absorb" the local atmosphere !
Enjoy !