I've ordered online several times and have for the most part been very satisfied- if you are not happy or have doubts about the item just send it back right away- I returned one thing and had no issue. I would live to shop in store but don't have a store super close.
I do both but since I'm not near a store I do order many items online...I did recently received a defective item and exchanged for another via online....sometimes if you are not familiar with a bag it's better to try in person....
I have ordered online many times, but that is partially because I don't have a LV in my state. I have always been very happy with my order and the shipping is fast. As an added bonus, when ordering online I don't have to pay sales tax since there is no Lv in my state.
I have also tried to order a few items online, but they were "call to purchase". I called and once they confirmed that I have purchased from LV in the past year, they called around the physical stores to track down the item for me and patched me through to the sales associate to order. I have been very pleased with the service. I have never had the need to make a return, so I can't comment on returns for online orders.
I would say that I prefer to order online, but I usually know what I want. If I was undecided or needed to try something on, I would wait and go to the store.