Not all Winnie the Pooh movies are made for younger viewers. Not all Winnie the Pooh movies can entrance adults as well as children. Both of these facts are acceptable and really only might cause a problem if they both prove to be true in a single Pooh movie. That, plus a few other issues, make Pooh's Heffalump Halloween Movie a subpar entry into the series.
The movie puts Pooh and the other somewhat more adult Hundred Acre Wood animals into the backseat for the majority of its runtime, instead focusing on Roo and Lumpy the Heffalump. Lumpy is unaware of the traditions of Halloween and terribly frightened by them, especially the one that Tigger pulls out of thin air, the story of the Gobloon who grants wishes if captured and turns people into jack-o'-lanterns if he captures them.
Predictably, Lumpy and Roo end up on a quest to capture the Gobloon and thereby save Halloween. Roo helps Lumpy overcome his fears, thereby giving the moral to younger viewers in the audience that Halloween isn't terribly scary and that they too can overcome their fears.
It's not a bad message to give, if only the "scary" moments of the film weren't actually kind of scary for younger viewers. There is nothing to actually be scared of, but between the creepy-ish music, angry-ish looking jack-o'-lanterns, quick cuts, and clear terror that Roo and Lumpy feel on occasion, young Pooh fans may find themselves frightened. Roo and Lumpy however are both characters which seem constructed solely to appeal to younger viewers, so one can't quite tell why the film contains any potentially scary moments whatsoever if it's going to focus on those characters.
Perhaps though all that is forgivable, after all, Roo and Lumpy are wholly absent from the portion of the film that is lifted directly from the Boo to You Too! Winnie-the-Pooh Halloween television special. The decision to include that though is also an odd one. Story-wise, that portion of the film is infinitely more compelling and less scary than the newer footage. Of course, the animation also looks significantly older than the newer portions of the film. Additionally, the older print has scratches, noise, and other imperfections which are absent from the newer portion. Even though it is included in the new movie as a flashback (Roo is telling the story of that Halloween to Lumpy), it still feels like an awkward juxtaposition.