- Awesome Music: Sega marketed the game's soundtrack heavily prior to its release, even providing interviews with composers Teruhiko Nakagawa and Tatsuyuki Meada, although the soundtrack's reception was rather mixed. Not to say there weren't some good tunes in there, such as "Killing Bedroom" and its expanded guitar version found on the soundtrack. But special mention has to go toward the final boss theme, "Megalomania".
- Cult Classic: Obscure even among Sega's more obscure properties, and is the least popular from Smilebit's other Xbox offerings (Jet Set Radio Future and Panzer Dragoon Orta). Nonetheless the game has a bit of a loyal following who loved the game and consider it another one of Smilebit's gems, and it even earned a surprising 9.0 score from IGN.
- Goddamn Bats: Almost anything that isn't a giant spider on the ground. Enemies from off-screen will fire projectiles at you or even home in on you without warning. They don't do a lot of damage, but they're annoying and can be hard to hit.
- Hilarious in Hindsight: When the game was first released, the game also drew comparisons to the Metroid series, with some critics expressing it's what Metroid could have been in 3D, before the acclaimed Metroid Prime was released later in the same year and revitalized the once dormant franchise. That said, Kelly bears some similarities to Samus Aran: Both are blonde and attractive female protagonists with enhanced superhuman abilities, they both utilize unique evolving space armor, and they even wear blue outfits underneath (at least until Kelly's gearskin evolves). Kelly's dialogue is spoken through Inner Monologue and sports a Beauty Mark, traits that would be given to Samus in Metroid Fusion and Metroid: Other M respectively.
- It's Hard, So It Sucks!: The game's learning curve, control scheme and difficulty was a major turn off for many newcomers and was blamed for its commercial failure. It also didn't help that the game's intended play style wasn't made more apparent. Of course, there are plenty who appreciated the unique challenge.
- Narm: Much of the story, and even with the mission logs, a lot of what's happening isn't made clear.
- Kelly's monologues in the opening and ending try to paint her as The Philosopher, where she ponders about life as well as the answers they seek behind Hebble's disappearance, but they don't really add anything to the (already confusing) story and aren't really even that thought-provoking. It doesn't help that her voice has a filter effect added in the opening for some reason, which makes it difficult to understand or hear what she's even saying.
- The cutscene before fighting the final boss, Ivaldi. Inside Kelly's mind, we see Dr. Hebble with two mutant deformed babies with wings, a photo of the mutant, Dr. Hebble as a baby as well as his mother as seen in the prologue - all while a nude Kelly goes across the screen with her back facing the screen.
- The ending picture, which shows a younger Kelly welding a fragment of Halley's core along with two mutant flying babies, with the phrase "Everything was in someone's hands... someone is like a god. [sic]"
- Nightmare Fuel: Quite a bit of it. The idea of Tir Na Nog's colonists being turned into mindless giant killer insects, and some being trapped as Halley Cores. Hebble beheading his own daughter and running off with her body. Then towards the end, the scenes with the mutant deformed winged babies, where one stares at the player.
- That One Level: Naglfar's Pit 1, the game's version of Platform Hell. You have to reach the top of the stage by jumping across several platforms with well-timed jumps and boosts. Many platforms are very far from each other, some of which can easily be mistaken for slopes.
- They Wasted a Perfectly Good Character: Every character aside from Kelly qualifies, as they all had untapped potential. Story-wise, Saburouta only appears in the opening cutscene and has one line in the whole game, and his background is never brought up in the game at all, so we learn nothing of his character. Poe, despite being an disembodied head and Gate's daughter, only provides certain details regarding missions. Dr. Hebble is a complete mystery, since none of his objectives and accomplishments are really made clear, and isn't seen proper in the game itself, potentially making him a Posthumous Character.
- Visual Effects of Awesome: Much like Panzer Dragoon Orta, the graphics for the game looked fantastic especially for it's time.
- Waggle: Having to hold in the analog stick buttons and the shoulder pads in order to fly and boost. You have to have either three hands or the patience of a saint in order to do well at the game.
YMMV / GunValkyrie