I love all this kind of supernatural things in Pokemon games so I did enjoy the Strange House a lot. I think I spent a lot of time in there until I got the Lunar Wing. I didn't know I could get that key item there so I came in with the only idea of exploring. About the maze system, it was a bit like Lost Cave in Pokemon FR/LG, and I found out how to go through it quickly. Now that I've beaten the league, I'm looking forward to catching Cresselia.
But I still wonder why the Lunar Wing? It should have been something like an item to catch Darkrai, or maybe Darkrai could have appeared inside the house after you had beaten the league. Maybe Cresselia was once there, fought Darkrai and lost the battle? So Cresselia dropped her Lunar Wing while she was escaping.
Well, I don't really know, but the Strange House is a cool house which I enjoyed a lot. It's a shame you can't do anything else there once you've explored it. If they had added some post-league features, it would have been amazing.