Open casting sounds a little scary. What does that mean? If you go they can cast you for whatever they want, then if you take the part, they can get you out to some location and then claim that because it was open casting you have to learn forty pages of dialogue in two days because you've been switched to a different character?
All in all, that wouldn't be so bad, within reason. Open casting sounds like open season, like the casting directors can just take potshots at you, wounding pride with impunity as you try to focus on your dreams. Open casting is also open to helping you realize your dreams of becoming a well-respected actor, because it can get you on the path of paying your dues to become what you desire to be.
The best thing about open casting is that you can walk in a nobody and come out with some great part that other actors are drooling over because you were in the right place at the right time. It's like Charlie and the chocolate factory in real life, where you could find the golden foil. You enter the open casting, and the bustle of activity and surreal quality of the atmosphere resemble quite closely the inner goings-on of the chocolate factory.