- Awesome Music: Many of their hits are very, very liked.
- Ear Worm: Like you wouldn't believe!
- Misattributed Song: Because of their status as the best-known Touhou remix group, expect the work of other Touhou remixers such as Silver Forest and Cool&Create to be misattributed to them, especially by the Western fandom.
- On the flip side, because IOSYS does work with arrangers, lyricists, and vocalists from other circles and songs that they've worked on sometimes appear on other circles' CDs, there is occasionally a point of contention as to which circle the song should be considered belonging to (for example, "Mizuhashi Jealoussic Park", which originally appeared on ALiCE'S EMOTiON's Chaos Flare album and later on IOSYS's Touhou Ageha).
- Tastes Like Diabetes: Some of the videos tend to fall under this. Just try to watch "You Should Drink Cucumber-Flavored Beer!" without having your teeth rot out.
- Tearjerker: The ending of "Alice -> Sweet" certainly qualifies. The Mayfly–December Romance fanvid really caps it.
- "Artificial Children", another Alice song, becomes quite sad when you realize it's about Alice wondering if her dolls have life or not.
YMMV / IOSYS
A general note about IOSYS themselves: While they are undoubtedly one of the most popular remix groups, there are those who hate what they do to the original songs, find their videos annoying, and consider them to be sell-outs for doing things like taking on commercial jobs and selling their CDs through Amazon. If you can get past that, some of IOSYS's more bubblegummy songs are hit-or-miss, and your feelings about the drama tracks will vary depending on your understanding of Japanese, how well you tolerate the characters' voices, and so on.