These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Follow the Leader: Both ways. In The Groove took the 4-arrow paradigm from DDR and ran with it, including new features like mines (which were already in Stepmania). Later, Konami added "mines" in their game, though rather than admit it, they made their "mines" lightning bolts that covered all 4 buttons at once, which limited their potential. Konami also started introducing some ridiculously difficult charts for some songs, but with no "bridges" to get there, so getting good enough to beat those charts basically required playing Stepmania or In The Groove.
It's Easy, so It Sucks (Every song under 10 blocks seems to suffer from this by the fanbase, despite a great deal of them actually being loads of fun.)
Thus this leads to more and more expert only Nintendo Hard custom songs and packs.
Good Bad Bugs - In the r21 patch for ITG2, players can play custom stepfiles, but the song cannot be tagged as being longer than 2 minutes. Emphasis on "tagged"; a little file manipulation can allow you to play songs longer than 2 minutes (though playing exceptionally long songs is frowned upon by fellow players and arcade operators).
In the updated r23 patch, however, this has been fixed; songs now automatically cut off at around 2 minutes and 30 seconds.