Having just read yet another supermarket angst thread (involvoing trollies), it made me wonder why so many people still do their food shop in this way...? Most of the online services are fantastic these days and so much easier. The benefits:
- Shop online from home at any time that suits you
- Many of the instore offers are available online
- You tend not to impulse buy so spend less
- You don't have to deal with dragging children round the supermarket - you could spend this time doing something FUN
- You don't have to deal with nagging for sweets/rides/comics etc
- You save petrol money
- Someone else packs your shopping and BRINGS IT IN FOR YOU!
Honestly, what's not to like?
Yes I know the 'I like to choose my own fruit and veg/fresh stuff' argument. I like to too but not that much lol 
And yes sometimes there are occasional problems with timing or items being substituted but in my experience these times are far and few between and the benefits GREATLY outweigh these.