I shouldn't complain too much as the price is right, but I will anyway.
I'm sure the game author thought it would be really cool to be able to play Snoopy and the Red Baron at the same time, as maybe your kids will be able to share a keyboard. Another adult is not going to sit next to me at the same keyboard.
I hate any game where I have to be a typist in order to play the game, as I grew up using joysticks, and there is a fat chance in hell of me bothering to learn 8 letter keys that all use the same (left) hand for navigation. Hell, I have a 5-button mouse. I could program the weapons to the mouse, unfortunately not the navigation (grrr).
I don't like the fact that game deletes the Menu bar, when a simple menu bar with New Game (enabling me to choose single player Snoopy, single player Red Baron, and two player modes), Save Game, Quit, Size Window, and Preferences (with the ability to choose my keyboard shortcuts) would be hyper-useful. Yeah, using the ESC key to quit follows Apple's Human Interface Guidelines.
I didn't expect much from the graphics, as someone weened on an Atari 2600, I'm fine with low-res graphics. However, I run a monitor in 1856x1392 mode, the game plays in a 512x380 window. The last time I had a monitor that small I was using an SE/30 running OS 6. Needless to say the game is impossibly small on my monitor.
In short this game is great for your 5-year old, beyond that it's just an irritation.