Unreliable. Frequent missed appointments in Singapore because no cars available or drivers repeatedly cancel to pick up nearer passengers. Acute problems at weekends and Fridays. These problems can be fixed. Hence 1*. Once you have had to postpone three important medical appointments, despite allowing plenty if time, you can only give it 1*. Grab has many solutions as options, but does nothing to resolve the problem of unreliability and service failure. Drivers generally 5* - when they arrive.