This material makes a character capable of unrestricted flight before level 5, so DMs should take note of that fact. Obstacles and traps reliant on falling/gravity/height may not be significant challenges to a character using this material. Obstacles of these sorts are, however, an excellent tool to highlight the character's advantage. If you are using obstacles of these sorts to restrain the players to the intended play area, it will likely be ineffectual at containing such a character. Additionally, throwing in ranged or flying opponents with most of your encounters is advisable, but not to the extent that it would punish the player for their character's ability to fly, so much as to give them something meaningful to compete against. Be careful about who is allowed to use this material, as immature players will likely abuse flight to derail the campaign. As should be standard, such players should be dealt with outside-of-game through open communication, but it is often best to avoid the situation in the first place. New players often have difficulties visualizing themselves as another person, let alone another creature capable of moving in ways that they themselves will never experience. As such, if a new player is allowed to use this material, they may need some degree of guidance to remember that their character can fly indefinitely without limitations, though it should only take a few sessions to really drive the point home.