[MrClean]

Depending on how old your son is, the ESC can be set so the truck has half the normal power. The brushless Slash is really fast compared to the brushed version. With the Lipo battery it can also increase the speed. The controller has a switch on it that controls how much trigger pull is applied to accelerating/braking, for beginners it should be 70/30. I belong to a forum with lots of good people with a ton of knowledge, RCNitroTalk.com.....don't let the name fool you, there is a ton of electric info on there.
Feel free to ask me any questions you might have, I certainly don't know everything but I've been in the hobby for several years now. Most important thing, it'll give you and your son lots to do together, enjoy brother!!