Not an expert, but one interesting feature is the ability to keep a connection open across network changes.

In TCP and UDP, connections are identified using local IP address/local port/remote IP address/remote port tuples. This means, if my IP address changes, (e.g. because I connected to a new WiFi network) all TCP connections that were active before must be abandoned. With QUIC, supposedly, an identifier separate from IP addresses is used, so there are ways how a connection could be resumed. (I'm fuzzy on the details though)