If something is done impressively, it makes people look twice and feel respect — because it is very good, very large, very skilled, or very important. The building rises impressively. She played the piano impressively. The team won impressively, not by a lucky one-point gap. This is a warm, praising adverb. It is common in speech and writing; it is not stiff. You can use it for people, things, and results. Though actually, people also stretch it: “impressively bad” is a joke, meaning so bad it still makes you stare. And impressively is about the effect on the watcher, not about whether you meant to show off. A quiet person can still do something impressively.