We've just used them in May for Stansted to Dalaman return flight and have to say that it was very good value. Meals and drinks reasonably priced, good leg room and staff very helpful. The exchange at Istanbul is a bit frantic especially as we had to get a visa - it basically involves moving very quickly from the internation arrivals floor up 1 flight to domestic departures (again the airport staff were very helpful in directing everyone) but having arrived at 1850 in Istanbul we were on the plane to Dalaman at 1930 then an easy 1 hour flight. On arrival at Dalaman we were bussed from Domestic to International terminal to get cases. In fairness 1 of the 2 cases got lost in Istanbul but was then delivered to our apartment in Fethiye the following day. I'd recommend them and we are using them again this summer.
