When reading Cicero's book II and III, I came away with some of the same feelings as Mark Hannah. His post is proof positive that the early bird gets the worm so to speak. However, I came away with a different sense of the reading than Mark did.
I agree that at times it can seem that Cicero is arguing from a power over standpoint. Mark made a very good point about the quotation on (134), which states that the eloquent rhetor utilizes eloquence that “can not only make him upright who is biased, or bias him who is steadfast, but can, like an able and resolute commander, lead even him captive who resists and opposes.” However, I do not see this as utilizing "power over" rhetoric.
I think Cicero is trying to create a strange synthesis of Platonic, Aristotelian, and Isocratean rhetoric. He states, "the principles of philosophy are discovered by such minds as have acuteness and penetration enough to extract what is most probable concerning any subject, and are elegantly expressed with the aid of excercise in speaking" (214). He also states that oratory depends more on ability and less on art because the orator deals with opinion more than fact. Cicero also argues that the subject shifts and changes so quickly that one cannot develop precise knowledge of oratory. So we see he is appropriating Aristotle's arguments that "good" rhetoric is based on what a reasonable person might believe, and that it seemingly has no content in and of itself, as Crassus argues several times.
He also, obviously, mimics the Platonic dialogues, while also reimagining Platonic philosophy. The best example of this is when he chastizes Socrates stating, "separated in his discussions the abiltiy of thinking wisely and speaking gracefully, though they are naturally united...hence arose that divorce as it were the tongue from the heart" (208). There are several arguments I could make on the separation of mind and body or Cartesian duality but I do not want to stray from the topic at hand.
I think what Cicero ultimately was arguing is that the purpose of rhetoric and eloquence was to move people. Many times they chatise men like Phillipus, who was "a man of violence as well as of eloquence."
Cicero is wary of men who use eloquence and oratory for nefarious means. I think he thought of oratory as the power to get things done by persuading people to the best course of action of the republic.
When I think of "power over" I think of kings, and emperors, and when I think of "power with" I think of democracy. Crassus argues to open the discussion of Book I by arguing that oratory can only exist in free, peaceful, and tranquil nations, and that men have the power (through oratory) to interest move and persuade their fellow man. I think that Cicero sees oratory as a means of getting things done, by persuading others that your cause is right and best for the republic, and less on getting people to do what you want.