Anyone I know who has flown with them has only had positive things to say, for the price you pay you don't mind the odd hour delay, every transatlantic flight I have been on with other airlines has been delayed to some extent. Infact US Airways cancelled our flight the day before a couple of years ago. I don't think you can complain at £400 for a flight with Martinair in the middle of the summer holidays
I've been regularly checking the flight status' on kayak and although the flights sometimes take off an hour or so late they seem to make alot of that time up over the Atlantic.
My opinion might have changed come the end of August, but for now I still think it's a bargain 6 hour delay or not.