Charm is something I have memmed most of the time. There's still alot of content in groups that can be charmed.
Semi zerging a mission and get 2? Charm one for dps and keep full songs going rather than worrying about mez. Free dps off a mob is hard to ignore.
When wanting to pick a heavy hitting charmed mob, (Longshadow5 I charm the 2 mini named spiders into each other to wear them down), zoom in with shield equipped, start song, back off, let song start to finish, nip back in again to let it land and you've saved a fair bit of damage being taken.
Definately a usefull and solid song. Even without the range, it's still great to use.