Oh that's a very easy YES!
And if you can go mid week in October... well, perfection. Its nice and quiet (weekends and of course the last week with all the holidays are very very busy!)
For one the weather is usually really nice, not too hot, not cold, sunny blue skies... Then you have the autumn colors everywhere, particularly Frontierland... It's gorgeous!!
Then of course the Halloween decorations and shows!! I admit I haven't really checked what's happening this year, usually they decorate Main Street and Frontierland, ghosts and pumpkins all around, including the Dia de Muertos skeletons and alebrijes in Frontierland. And when it gets dark and all the lights go on... really beautiful.
I love the halloween parade, it's one of the best, and last year's new additon of the phantom manor float is really excellent.
Characters wise there are a few villains around, plus some cool costumes for MIckey and his friends.
So yes, definitely worth checking out!!