- Broken Base: There are those who enjoyed the Grand Finale, feeling that it was a good way to close out Danny's journey. Others felt that it was an unsatisfying capstone to an unfortunately lackluster final season, thanks to wasted plot elements and character behaviors such as his friends and sister (especially Sam) appearing to care more about Danny as a superhero than Danny himself. The fandom is so divided on this final episode that any fan work set after the end of the series always clarifies whether or not Phantom Planet occurred in the continuity of their story.
- Ending Aversion: A sizable number of the fanbase prefer ending the series with the previous episode D-Stabilized rather than this episode, feeling that the former was a more satisfying story. Aided by the fact that, either way, the audience is left with a lot of unfinished plot threads.
- Fanon Discontinuity: It is not uncommon for fanfiction to either ignore the finale's events or undo them.
- They Wasted a Perfectly Good Plot: Part of the above comes from the movie introducing several ideas that aren't used even close to their full potential.
- Over fifty years earlier, hero vs. giant-falling-space-rock-made-of-the-one-element-that-can-harm-his-species was the plot of the most popular episode of the first superhero series in history. It should be the easiest plot in the world to do right in a superhero series, making it doubly tragic that it generally wasn't, in this case.
- Valerie (Danny's first love and one of his most prominent foes) learns his Secret Identity, with the episode directly prior to this dealing with her changing perspective on the ghost boy. Her reaction to the monumental discovery that her ex-boyfriend and her Arch-Enemy are one and the same is lumped into a generic crowd shot of people smiling and clapping. This combines with her lack of role in this episode, and the season as a whole, to become a huge case of Aborted Arc.
- A team of teenaged villains who hunt ghosts for money are introduced in the very last episode, when they would have made an excellent recurring foil or even Evil Counterpart (with Biting-the-Hand Humor, considering that a similar team served as inspiration for the series, and were the good guys).
- The episode also introduces ectoranium, the ghost-equivalent of kryptonite. Again, being the last episode, the endless possibilities this could be used for are left completely unexplored.
- They never show how Dash and Paulina (both admirers of Danny Phantom) reacted upon Danny revealing his identity. Especially Paulina, who has a big crush on Danny Phantom, who's officially going out with the "goth geek".
- Unintentionally Sympathetic: We're supposed to be upset with Danny for choosing to give up his powers. This ignores the fact that he had wanted his life normal again and did this to save his parents from getting arrested from unknowingly harboring a ghost. Add to the fact that his friends and sister were disappointed with him, and Sam in particular calls him selfish, even though he rightfully defends himself by admitting he cares more for his loved ones that his powers. Sam's answer to this, about how he's just a normal person and not someone amazing, doesn't make Danny less sympathetic, only more since it comes off as his loved ones only value his powers.
YMMV / Phantom Planet