I am curious about this too. We will be in DL the last weekend in October, and Mickey's Halloween Treat will be on the second of our two nights in the park. Is it worth giving up the second night in DL to come to this, or should we just spend our normal relaxing evening in DL??? It would probably just be my DBF and I going to the party if we did so.
I think it's fun to see everyone in their costumes, and the rides have less of a wait when you go. Also, last year, all the Paradise Pier Boardwalk games were free, but I think all you won was candy.