
I've had several friends talk about how they think Anakin choose the Dark Side too quickly - fell too easily. I would argue that he really didn't have another choice.
From the beginning the Jedi didn't trust him. Windu flat out said he wasn't to be trained, Yoda not only looked scarey in EpI, but he didn't say anything to make the boy feel welcome either - "See through you, we can." So if they weren't going to train Anakin - what was Qui-gon to do? Send the boy back to slavery on Tatooine? Doesn't sound like the caring, compassionate Jedi they should be.
Over Anakin's 13 years in the Jedi Order, only one man never doubts him - Palpatine. He encourages him, trusts him, believes in him, never scolds him - wrapping his web around Anakin so quietly no one sees it until it's too late. Obi-wan is too by the book to understand Anakin's emotions, Windu doesn't trust him at all - but will gladly send him to death in the War, and Yoda only dispenses cryptic advise that Anakin should rejoice when one he loves dies.
Anakin want's to be good - do the right thing. He goes to Yoda first looking for advice about his dreams. He turns in Palpatine to Windu when he learns the truth. He knows he's being impatient and that Obi-wan has his best interests at heart. But Anakin's greatest strength is also his greatest weakness. He loves too much.
His mothers death cuts his heart - he was too late to save her. Perhaps if Obi-wan said "Alright, let's go look in on her - make sure she's alright." Perhaps they could have saved her. The thought of loosing his good friend Palpatine drove this point home. Then, dreams of loosing Padme were too much to bear - he couldn't let it happen again. He wouldn't arrive too late this time. He would take action - stop it before it would happen. Whatever it takes - whatever the cost.
Yoda once said - "If you choose the quick and easy path - forever will it dominate your destiny, consume you it will."
Anakin has wavered on the line between the light and the dark. But once he 'chooses' the Dark Path - the floor drops out from under him. With each step he decends quicker and deeper - filling with the power of the Dark Side. It whispers promises of power, of abilities to do and have all he desires. It's siren song lures him deeper and deeper - All the power he craves, an end to fighting, order, peace.
At last, when he believes the two most important people in his life - those he loves most - have abandoned him, his heart shatters. His rage lashes out and he desends into the fire of hate.
No, Anakin didn't fall too quickly - he had been falling for 13 years.