Elise is vulnerable but flexible. She might have a lot of threats but she has ways of dealing with most in her own way. Being ranged top is usually an advantage, with cc burst at her own disposal to handle squishier targets.

She can split push fairly well and her kit grants her invading/roaming powers and rift soloing capabilities, as well as CC for the jungler ganks. It's a bit of a niche pick but with the right match-up/team comp it can do very nicely.