I bought this game last year having read the reviews posted on Amazon. It is brilliant.
Initially, i played it against only with a gaming friend of mine and we quickly went from having no idea about what strategy to use, to thinking quite hard about what we were doing. Like any number of great games, it's very easy to learn but you could play for years without ever perfecting a single winning tactic.
That said, if you don't want to put that much thought into it, it's still a really enjoyable game. Unlike, for example Scrabble, you're not having to think in a way that warrants silence and deep concentration; I've taken it to the pub to play with mates and you can play whilst chatting away (and drinking). I've played it with my family, who are increasingly resistant to elongated instructions, and they all got it and enjoyed it.
For all it's simplicity though, there must be a key to winning - i rarely beat my gaming mate and my partner rarely beats me.
No little warnings, or slight negatives, this is a fantastic game and i'd recommend it happily to anyone.