I've been using Grubhub for several years and for the most part I've been pretty satisfied with their service. On the odd occasion there is a problem with the food or delivery, I let Grubhub know in an online chat and they refund my money and usually offer me a discount on my next meal.
I don't eat fast foods or takeaways - they always taste manky to me, but that is probably my taste lol. I prefer to make my own food and then I know what the experience will be like. Of course I have the time to do that, so others may not and having food brought in may be the most convenient way for them. Personal taste.