This subject elicits a strong response in me because I just finished my first year of teaching last year in a Title I district. I actually attended education courses with other TFA corps members for a year while we all dealt with being "thrown in" to a largely dysfunctional system. (Admittedly, I applied to TFA--my first job interview ever!--and was one of 15,000 or so rejects... the program is quite a bit more selective than a district or state teacher training program.)
I discovered, however, that even the Princeton and Georgetown grads with whom I worked rarely received any special treatment simply because of their lofty educational goals. These teachers were only able to break through to their students once they forged relationships, because quite frankly, it doesn't matter to a low-income kid who doesn't know how to read if you had the highest GPA in your class.
I had a rough first year in the classroom. I received a high rating as a first year teacher, but I know of the many ways in which I could have done better--if only I had had the time. Maybe I would have done better if I had taken more education coursework, but I also should have practiced more of the basics before entering the classroom.
I think that TFA is a great organization, but it does need to make some improvements. Teaching certainly takes more skill and patience than I ever imagined, and even brilliant Princeton grads need time to adjust. Also, there are a few of us "rejects" who would have benefitted from some of the more rigorous TFA training. Additionally, a large percentage of TFA corps members do leave teaching after their two-year stint, but I believe that this is largely because most are quite young and are still making major life decisions.
Several people I met simply entered TFA to "try out" teaching, and many will move on simply because their personalities and interests may be better suited to other careers. For example, one just re-entered medical school. He will probably be a greater asset to society as a neurosurgeon than as a high school biology teacher. But at the same time, he will always be an advocate for education reform.
Teaching is one of the most difficult professions--certainly not for the faint of heart. Fighting poverty, drugs, crime, apathy, language barriers, social barriers, and illiteracy to finally reach kids... it is quite an adventure!