There's a lot to like for AT fans in this game. It's essentially Civilization distilled down into a concentrated paste, minus the warfare*. The board is random, resource production is random, there's tons of compulsory interaction, a few chances for total screwage, and it's always tight.
The game is a triumph of design--the modular board keeps rounds fresh. The combination of open information (how many resource cards do you have?) and hidden information (what -are- those cards? Victory Points? Knights?) keeps everyone simultaneously in the know and guessing. The balance in the resource management element is also so well done, it's no wonder that is has been copied countless times since. You need resources, but if you hog them, you might get burned. A player can try to win on her own, but she'll fall behind fast--there's a constant hustle for goods. The beginning game's demand for brick and wood slowly creeps to stone and wheat production as players get more established.
There's so much to like in this game, it's hard for me to justify not recommending it universally.
*(Dearth of warfare remedied by Cities & Knights of Catan expansion).
Easy to learn and a fun way to spend a couple hours. Like any trade/negotiation game the group you play with can impact the flow/fun of the game a lot. It a combination of the greatness of this game and the weakness of it's successors that Settlers- which started the Euro Board Game invasion is still one of the best in the field.