Forgive me, but having only sailed with Disney and NCL, Im going to be comparing NCLs iConcierge app to the Disney on-board app.
Having access to the Freestyle daily is great, but Id like to be able to mark events as favorites so I can get reminders when one is about to start (the DCL app does this). Being able to review my on-board account was extremely helpful. Having to pay $9.99 ON EACH DEVICE to be able to do phone/messaging is a bit excessive. The features worked fine, but for a family of 3 this meant $30 to be able to call/text each other while on the ship. On Disney, messaging through the app is free. Being able to browse port excursions is a nice addition, but that area seemed to cause the app to freeze more often.
windracer_jr about Norwegian iConcierge, v3.0.28