the Balloons don't really add much to clumsy ninja. They can be used to demonstrate the physics in the game and put the ninja in some funny predicaments, but they don't generally provide much XP. Once you pop them you receive the XP payout, so feel free to experiment in making your ninja fly and glide around the arena, but remember that you won't get anything back until they're popped.
When compared with other ninja Kit items they do at least offer a quick payout - you don't have to complete complicated training regimes to get your XP.
Below you will find a list of the Balloons in clumsy ninja along with their key stats:
Cost: 10 Coins (for 5 Balloons)
Earns: 25 XP
Unlocked: Level 1
Cost: 25 Coins or 4 Gems (for 10 Balloons)
Earns: 430 XP
Unlocked: Level 9
Cost: 50 Coins or 6 Gems (for 10 Balloons)
Earns: 1,100 XP
Unlocked: Level 16
Cost: 75 Coins or 9 Gems (for 10 Balloons)
Earns: 6,300 XP
Unlocked: Level 30 (Level 9 with Gems)
Cost: 100 Coins or 10 Gems (for 10 Balloons)
Earns: 10,000 XP
Unlocked: Level 36 (Level 11 with Gems)
why do my multi bloons give me 2000 xp