Giving away flight at 1st level isn't necessarily a dealbreaker, but it's generally a no-no. While it's not amazingly overpowered, the vast majority of 1st-level encounters have no ranged attacks or flight, essentially making the character invincible. In addition, there's a grace period when the party doesn't have flight where the canyon of death or the evil forest can itself be a credible challenge. Having this character in the party means that a canyon can never be a threat to the party, which limits the sorts of things a DM can do in the adventure. It's not gamebreaking, but it's generally accepted that levels 1-5 flight is hard to come by so that these kinds of challenges can exist in the game.

For comparison, the warlock and dragonfire adept get flight at level 6. Fly is available as a level 3 spell.