* AlternateCharacterInterpretation: Irys. Is it a monster who drinks the life force of living beings with reckless abandon, and torments Ayana with memories of her family being killed, or a tragic case of Ayana's hatred twisting a guardian’s psyche to the point that it doesn't even know that what it's doing is wrong? The film doesn’t give an answer for either interpretation, leaving it up to you to decide.
* SugarWiki/AwesomeMusic: Kow Otani is at the top of his game here, with several great pieces near the end, such as:
** Offense and Defense, when Gamera fights Irys in the sky.
** Descendents of Antiquity, when Ayana is racing to the front of the station to see Irys out in the city.
** Kyoto In Flames, plays when Asagi and Nagamine try to convince Ayana that Gamera isn't her enemy, while Gamera and Irys fight each other.
** The Red Lotus Flame, which plays when Gamera kills Irys.
** The Guardian Beast, which plays when Gamera revives Ayana.
** Ending Theme: Gamera 1999, which ADV used as the music for the DVD's main menu.
** And, while not composed by Kow Otani, we have Julianna's song, Tell Me Once Again, which plays over the end credits.
* EvenBetterSequel: Considered by many the best entry of the Heisei Gamera trilogy.
* SacredCow: Gamera 3 is widely heralded by Kaiju fans as not only the best film of the Heisei trilogy, but also of the whole Gamera series, as well as one of the defining films of the Kaiju genre, often favorably compared on par with ''Film/Godzilla1954'' in terms of writing, drama, themes and special effects.
* TearJerker: When you realize that this is the last movie in the Heisei Gamera trilogy. Everything in the film also counts to an extent, from Ayana's tragic past to Gamera's own treatment despite how he's only doing what he was created to do, and even Osako's life going downhill so much.
* UnintentionallyUnsympathetic: Ayana. Despite losing her family she's thoroughly unlikable throughout the film and thinks everything is all about her. [[spoiler: It's only after until being absorbed by Irys she sees the true magnitude of what she's done.]]
** Though to be completely fair it's clear that the girl has some ''severe'' mental problems and at some points she even seems borderline suicidal. It's extremely likely she has PTSD or another form of mental strain/damage.
* SugarWiki/VisualEffectsOfAwesome: While the CGI varies in quality, this being 1999 where CGI was still in its infancy as far as live-action was concerned, the movie has some of the '''absolute''' best suitmation, miniature and puppet effects in the entire genre and is a testament to just how truly great the effects can get when utilized to such an extent. There are some genuinely striking and awe inspiring shots in the film.