The main issue with Scoot is lack of flight frequency / network when (inevitably) a flight does get cancelled. From memory in the last half a year I believe there's been two cases where a Scoot plane got grounded cos of maintenance and the passengers were all stranded for over a day.

Having said that, from casual observation between myself and my brother in law, from about 10 flights total, 2 of them were delayed by around 2 hours.