I have listened to much learned discussion of his immaturity, the "cloud" over his father’s credentials, the splintered nature of his movement and forces. All true. He does often seem to be channeling" the Mad Mullah stereotype that so thickly populated old movies like "Drums," one of my favorites.
In spite of all that I think he is probably the man of the future in Shia Iraq. The coming departure of the British from the south of Iraq will signal the onset of all out struggle; political, paramilitary, and financial for ultimate authority in the Shia run parts of the country.
Shiism is a social construct (and faith) of the disinherited and hungry. He stands for the Shia poor and their ultimate dreams. The secular world thinks the idea of the return of the Mahdi/Occulted Imam is absurd, that this supposed belief must be a fraud on some level. The poor men who carry guns for Moqtada do not think it is a fraud. they believe that the Mahdi will return soon to restore justice to the earth and that Jesus will come with him.
Moqtada has had a difficult time disciplining his growing "forces." This was inevitable in a grass roots movement made up of human material focused on salvation and looking to him for leadership rather than command.
Whether or not one thinks that he was somehow responsible for the recent tragedy at Karbala, it is now clear that he is going to take the opportunity provided by that event to reform his movement and to seek command of those who say they follow him. We will see if he can do that.
Sadr, IMO, is not really focused on the coalition or the American forces. He is waiting for them to leave. When that happens he will seek to become the power behind the prime minister. pl