My Ocado experience is mostly good – time slots when I need them, good value for good products. Drivers are mostly very polite and on time, hence the "good rating".
On the downside; some of the fresh food can have short use by dates, bags can be over packed and food damaged or has just one item. One or two drivers have been very rude, but that is not common.
The biggest worry, with Ocado, after being a customer for a few years is if something really goes wrong, which has happened a few times. Problems happen in all business and how they respond is the key and I am not always impressed by the way they cope with the big problems; they need to take some more responsibility and show some leadership when these rare big problems occur.