Really? We went on Halloween last year, which admittedly was on I believe a Wednesday, and I thought it was fairly uncrowded. I think our longest wait was for food at Riverbelle Terrace. Admittedly, we spent a large chunk of the afternoon running around DCA until it closed and then we went back to DL, but I really enjoyed myself and never felt like it got too crazy/crowded.
From what I understand, the crowds are definitely getting bigger every year. Now how that compares to the summer crowd, only a regular could tell you. I only know what I've researched for my own trip last week of Oct. Disneyland has expanded their hours this October from the last few. They also added extra days to Mickey's Halloween Treat. They wouldn't do that unless the larger crowds required it. Likely the crowds are smaller than peak season, but not nearly as small as it used to be this time of year- as the Halloween Season becomes more and more popular there.