I think the key is to have just the right amount of railroading.

On one hand, I don't want to be told, "THIS IS WHERE YOU MUST GO NEXT, YOU HAVE NO SAY." But on the other, I don't want to just be left wondering what the hell I'm supposed to be doing and if I'm in the right place. I think it's good that the player has options, but that game somehow tells the player - via quest chains or what have you - what those options are so that they can choose accordingly.