It's rather slow paced IMO, the extra money you can get with better upgrades doesn't scale very well. Sure you get double the money, but you're also flying in the air for twice the time. So it's rather boring...Another place this shows is with nukes, they rarely even break even. The "luck" factor is also different from the other shooting&fly through the air games but the flights are too long and the reward little in comparison so they can be frustrating at times.
The game is great and fun to play, but the lack of save really kills it because the controls aren't smooth enough to actually bring "skill" into the game. It's more or less guessing which weapons are worth the money and moving under the balloons. For example, upgrading to laser basically killed me because the thin beams just went right through the balloon gaps and I couldn't move fast enough to aim. (I could react fast enough, but the monkey doesn't follow the mouse, it trails behind it)
Nice game but I can't see the money I earn after each level, it's blocked by the "more games" button. Also, you can't earn your money if you don't survive to the end of the level, which isn't in line with being able to achieve your goals and still die. Not sure if intended or not.
There's a really annoying glitch when you click the restart level button fast, the menu is stuck as a background and doesn't go away unless you refresh the whole game