Have been using ocado for past 18 months and consistently impressed with the service, and the quality of produce, ( my reason for changing from other online supermarket was that their fresh produce arrived in a poor state and had to be thrown away).
Love the smart pass, which means I have more frequent , but less costly shops, I use the app in my iPad as an ongoing shopping list and place order when over £40.
Drivers are always helpful, polite, and if they want to come early they ask if it is convenient, rather than just telling you they are.