The one who lived

Tereza, a ranger known as Ruunya, was thought to be dead by everyone close to her. She makes it known that she is alive when Strider goes to the Prancing Pony to wait for the hobbits. Tereza joins the Fellowship and helps them on their journey. Does she prove to be valuable where she goes, or just another burden? (Copyright of all Lord of the Rings characters and locations along with plot but tweaks and Tereza belong to Tolkien.)