Harry would be very unlucky if he met Hel. Hel's afterlife in some ways is far worse than most. It's an endless place of all suffering and hunger that never allows people to leave. Hel was pretty dominant in her own Realm, even Odin ended up respecting her there. Hel robs beings of their ambition, of their energy, of their minds. Constant coldness and dark, everything chilled down to nothing. Hel has no challengers in her Realm. No Viking dared disrespect her, and all feared going to her Realm. It's not just about torture all her beings are her slaves, and are depressed. Even Baldr the God of Light and Beauty was a shadow of himself in her Realm. Not to mention her body was half dead half alive.
The Greek Underworld is nowhere near as scary, in my book. Except for Tartarus maybe.