We just finished watching this and all enjoyed it, my youngest son who's 7 is on a second viewing, so it's safe to say it went down well.
I must say I'm not the biggest fan of these 'buddies' movies, I find them a little boring and predictable, though my kids love them and I suppose that's who they're aimed at . All that said, I did actually get into this one. The story line is much stronger than previous ones and the halloween theme is great, a little creepy but not really scary even for the youngest of viewers.
If you want something different to watch this halloween with your kids then I'd definately recommend, even if your not a fan of the other films in the series.