Personally, I love solitude. As an introvert, I find peace in the quietness of being alone with my thought and with God. I have to say though that the intentional discipline of solitude is very different. I decided one time to get away and stay in a cabin for a 3 day spiritual retreat. It sounded good, but in reality, it was one of the most difficult things I've ever done. I seriously felt like I was going mad in the silence as the ticks of the clock began to slow down. I don't think we realize how dependent we become on things to entertain and occupy our mind. It's very difficult to make any spiritual progress the first time you practice solitude. Your mind screams at you to do something, anything to occupy your thoughts and pass the time the same way your stomach screams to be fed when you fast.
Willard says "In solitude, we confront our own soul with its obscure forces and conflicts that escape our attention when we are interacting with others. Thus 'Solitude is a terrible trial, for it serves to crack open and burst apart the shell of our spiritual insecurities. It opens out to us the unknown abyss that we all carry within us'." We can never hope to truly experience transformation in Christ until we face the inner man. We can hear Truth a hundred times and respond positively a hundred times all the while, the inner man remains untouched, tucked away in the deep recesses of our psyche. Solitude brings us face to face with our own false sense of self and its not pretty. The end result though is freedom. If we can press through this discipline and allow God to truly deal with us on this level, we'll experience a new freedom in Christ that we have yet to know. This is one discipline that's essential to the spiritual growth of a disciple.