I've done the 120-hour online TEFL course and I've been very happy with it. I've studied Languages and I have four years of teaching experience, thus the course did not surprise me with the level of difficulty. It took me only 2 weeks to complete it.
Nevertheless, I truly enjoyed the units focused on teaching, class management etc. It was really nice to get back on track with all that knowledge after a 2-year break in teaching. I particularly liked writing lesson plans as the self-evaluation tasks.
Moreover, whenever I had a problem, the reaction on the support center side was immediate and very helpful. ITTT provides you with a lot of additional materials and some nice surprises at the end of the course. That was definitely a pleasant and unexpected bonus.
My only worry is the recognition given to this course. CELTA seems to be the first preference among all the employers and I will surely do it at some point in the future. However, TEFL from ITTT is a much cheaper option and it prepares you rather well to become a teacher, especially if you have previous teaching/linguistic preparation. It puts you on the ELT market and serves as and incentive to continue learning (CELTA next!).