Strengths; Cheaper, value, good quality, grocery run is the best website for online groceries. Weaknesses; damaged from transport (unlikely to happen if packaged properly.) So I would say online groceries aren't all that bad. Actually, they are pretty great! But I highly recommend Grocery run because they have a great range of products, quality service and they are a reliable company.
Assuming you are talking about the benefits and disadvantages of chopping for groceries online, the first thing would be convenience. With online shopping, you don't have to leave the comfort of your home to get groceries. The biggest disadvantage is that the groceries might never arrive. Shopping online also saves you money because you don't have to drive to the store.
It's definitely convenient and especially helpful for the elderly and those who have limited mobility. Besides the obvious downside(missing items, late delivery, etc...) is when shopping for produce, I'd think most people like to select their own. :)