This game is certainly well worth the money, especially seeing as it's so cheap. It's massively difficult, but that's part of the charm. As you go through the various levels, it'll be a different experience each time, with only a few major stages kept the same. Every level almost never failed to make me laugh out loud, due to both the randomness of the situation and the sheer ridiculousness of it's difficulty. You'll end up smiling as your wagon is sucked into a tornado along with some buffalo, only to immediately stop as one smashes into your wagon, killing the one person dying of Typhoid. You'll feel a sense of relief after surviving an avalanche, only to feel a deep sense of dread as wolves attack during the next avalanche.
As you progress through the game, you'll come across multiple random encounters, and if you survive them, you'll recieve an upgraded weapon (until you die) and/or a new wagon (to keep forever, across all new games). The new wagons, as well as keeping up with the game's humour (e.g a UFO wagon that fires laser beams), will each have both an improvement (larger projectiles, splash damage etc) and a flaw (harder to control, lower rate of fire etc). It's up to you to decide which best suits you.
While the gameplay is certainly good, if not utterly frustrating, the soundtrack alone is a good reason to buy the game. For the low price and sheer replayability, it gets a well deserved 8.5/10 from me.