Because it's somewhat harder to execute notes timing/accuracy especially on high difficulty charts (start from 28+) without proper device.

Device dependency, than any other mobile rhythm games out there. More grinding and farming if the game get a comparison with other gacha rhythm games out there (these are optional tho).

Hard to get limited ssr card you wants, except being a lucksack or whale. difficulty level display on the results screen). Lack of game settings and maybe lack of something common which can be found on other rhythm games (e.g. There are autodelete features, but still nope for virtual live data cmiiw. The game size is too big, especially if download with some MVs or virtual live datas. Even, some features are basically for players who likes to simp or oshi + Have some feature which can't be found in other gacha rhythm games. Including another vocal version, so some song have a bit change of lyrics and feeling/atmosphere. + All of 5 groups have a lot of great songs, especially Vivid Bad Squad and 25ji. + Keep releasing new charts and commissioned songs, so that's including introducing some vocaloid song producer and no more hibernation for the popular one. + Popular voice actor or seiyuu, mostly come from rhythm, music, or idol series. + Original project sekai characters are likeable and have good vocals or covers. + Very care for story NPCs (like it have an unique art), tho i'm not a story reader. + Beautiful card artstyle which difficult to describe. + Side flicks on Proseka can be ignored and it does not affect to combos, despite accuracy will be ruined. + Recent songs have some new gimmicks, tho those only for high difficulty charts right now. + Fun (or pain) notes based by song lyrics. + Have different size of notes (especially big notes) as an unique mechanic, so higher difficulty charts are more challenging for player. + Several QoL features, imo the most important is changing the amount of live bonus (stamina) consumption per run or song, it can be set to 2 or 3 for optimal rewards or 5~10 for faster run. + Simple UI and not stressful for eyes and brain. + Have a lot of great 2D and 3D music videos (MVs). + Have 6 vocaloid characters and male characters. So, it have a lot of active players in game. They are known for their unique musical style.+ One of the best JP rhythm game right now. GHOST, also known as GHOST and Pals (formerly Marz Mitzi and ghostie), is an illustrator, music producer and video editor whose songs utilized vocal synthesizers such as VOCALOID or CeVIO.

List of vocaloid charters