From what we know of it, how do you rate Raventree Hall as a fortification?

It’s a standard castle – stone walls, defensive towers, moat – but it’s pretty solid. Not up there with the more crazy Westerosi castles like Storm’s End, Casterly Rock, the Eyrie, etc., but definitely better than your lesser wooden keeps. Somewhat less strong than Riverrun, since they have a regular moat rather than rivers.