When something is so bad you're shocked by it, atrocious may be the only adjective that fits the bill. In an exaggerated sense, atrocious can refer to something tasteless or unbearably bad. For example, "She was wearing an atrocious hat," or "His spelling was atrocious." In these examples, the offense is relatively minor. But atrocious can also be used to describe something of much greater offense marked by extreme cruelty.
Great is an easy word to overuse, in part because it covers so much ground. It can mean important, vast, or even skillful. But when you're looking for a more lively and emphatic term to describe something as excellent or first-rate, wonderful is a nice option. Wonderful, in its most literal sense, means "full of wonder." It connotes a sense of astonishment, surprise, or admiration, which is perhaps why it's so frequently followed by an exclamation mark! But be careful, because just like great, wonderful can be used in an ironic sense to mean just the opposite, as in, "After arriving late to a meeting and seeing his boss look at him angrily, he sighed to himself, 'wonderful.'"