I will begin by saying that I absolutely recommend the ITA to any person looking to get ESL certified. I took the online certification, so my review is about that option in particular. It was perfect for someone like me who was already working full time and couldn't take weeks off to go do an on-site class. There was enough material to keep me engaged throughout the several month period, but not so much that I couldn't handle the workload. My assigned teacher was there only really to assist if we had questions or problems- I don't remember her doing any real teaching. In that way it was sort of a self study thing, so you do have to be motivated on your own. The coursework was designed in such a way that we had to read the material carefully though, and I thought that the content was of great quality.
Unlike most online courses, the ITA requires students to complete practicum hours which, while potentially difficult to find without assistance, make you more marketable upon completion and enhance the learning experience.
There is tons information avaialable for students as well. Job search info, country-specific information, alumni testamonials, and more. The most valuable part of the whole program and experience for me has been gaining access to the alumni network. I have met ITA alums in several countries and been in friendly contact with many more. Most are very happy to answer any questions you might have, and their photos, blogs, and videos are invaluable insights to the places they are.
ITA was one of the more expensive options, but for what I've gotten, I think it's worth the price. I think this course is the ideal choice for teachers-to-be who are eager and motivated!