Worf was a great addition to DS9, come on! He’s even more interesting than he was on TNG.
If you want one horrible mistake - take a look at the holographic jazz singer, whatshisname.Vic Fontaine a mistake‽
Maybe it is just because I like that style of music, Vic Fontaine doesn’t seem like a mistake to me.
I don’t like his type of music, but even if he would do something like classic rock, I would still find it annoying. Just like Uhura’s singing in TOS - I love Nichelle and her voice, but it just doesn’t fit to Trek.