Satellites are a great way to participate in bigger tournaments for a smaller fee... If you win them... But, like any other poker tournament, competition will be fierce, and unlike normal tournaments, only a very reduced number of players get to "the money", sometimes there' will only be one seat available to the next round.
So all in all, satellites tournaments can be a double edged sword, since you might spend more money in satellites than you would by directly buying in to the objective tournament.