Imagine yourself as a car traveling across the French countryside. You have 1000km to go, but you've got competition who keeps trying to thwart your efforts. You'll cause them to have accidents, repair your own, run into speed limits, and maybe even run out of gas once or twice. First to 5000 points (over several hands) wins the game.
This is a pretty simple card game--I can recall playing my mom's 1971 version (which I still use!) when I was a kid. Essentially you play milestone cards, ranging from 25km to 200km, any time you have a "roll" card in play. Opponents can play a "stop" or any of four maladies (like a flat tire). Certain cards can be played as preventative measures, like a puncture-proof tire, to avoid worrying about those cards.
There's not a lot of strategy involved, aside from having to keep just six cards in your hand at all times--often you'll be forced to decide whether you want to discard a roll card in favor of keeping a malady to play on your opponent, or you might cringe when you have to discard a 200km card because you're under a speed limit.
Like I said, it's a simple game: there's not much thinking involved, and it moves pretty quickly (which is a good thing, since 5000 points takes a few hands to reach). If you're looking for something that lacks some depth, something that's just plain fun, then Mille Bornes is a good choice. It plays fine with two people, should be good with four, and can be played with kids (perhaps of 6 or 8 years and up).
Here's where the "frustrating" part comes in. When my wife and I played the other night (I'll write up a session report for that), we encountered one of the annoyances: it can be a very long time before you're able to play a roll card, and in that time your opponent might be playing hundreds of kilometers of milestones. I should note that the directions call for removing some cards in the deck for a two-player game, but we didn't try that--it may well rectify the problem. Even so, it wasn't overly detrimental. However, this did cause the game to go a little longer than we might have liked; it's rather frustrating and boring to just sit around waiting for a card to come up.
An alternate rule might allow you to draw from the discard pile, rather than just the draw pile, since it was somewhat common for one of us to discard a roll card when the other needed it! This would certainly add a measure of strategy to the game, since you'd need to make sure to not discard something that would benefit your opponent.
Overall, it's a good game. It obviously doesn't have the depth of some games, but what it lacks there it makes up for in simple fun. I recommend it for one-on-one games as well as for the whole family.
I enjoyed it most as a 4-person, 2-team game. Can be frustrating, just get the Roll card only to get hammered by another accident/flat tire, etc. But that (and the minor taunting/teasing that goes with discarding the cards that the other team needs!) is part of the fun of the game.