Compare Online Grocery Shopping Sites

I'd like someone to research online grocery shopping and give a comparison of the websites that various supermarkets offer.

You won't have to order any goods but you would need to register on the site, navigate around the site, place goods in the basket, look for good offers/discounts and write a short report from the perspective of a new customer about how the experience was pointing out good or bad things you've found.

I want a short report for each site (there are four) and then one report comparing them and coming up with an overall winner.