Judging from the Bard class mod, the Bard is all around rather whimsical or wholesome depending on the situation. A small sampling in the spoilers below, including one that actually changes a fight significantly.
- Bards have two class dialogue paths when talking to Alfira. One has you help her directly finish her song, the other really discourages her.
- There's several Bard-specific dialogue options during every meeting with Volo, mostly either sassing at him or joining in with his exaggerations.
- Bard gets to roll a performance check to basically rap their way past the Goblin guards into the Blighted Village.
- You get the ability to break the tiefling child free from the Harpy song by essentially singing a Countercharm, and the Bard then becomes completely immune to Luring Song for the duration of the battle.
