depends how much time you want to put into it. If you want to really try to rank draft picks, manage your minor leagues and engage the waiver wire and league chat, then yes, it is worth it. Like most of life, you get out of it what you put in.
once in a great while, you might find someone needing a mid-season replacement owner, which you might be able to nab for free (though they generally want a long term commitment). Other than that, I don't know of a free way to try unless you have built up some wifs credits from other games.