Hi, I did my TEFL certificate with i-to-i a few years ago and it was great as I had no idea how I would teach or where to start. After 3 years of teaching now I think that a TEFL cert. is nearly a requirment in most countries and if it's not you can get paid more for having one. That's what happened in my case as I had a 100 hours one.
However I have heard some people saying that i-to-i is not really recongised anymore but I have no idea about that to be honest. I think that some employers would take it and others wouldn't. Personally I think that experience is more important but alot of jobs pay more if you have a TEFL Cert.
Where are you planning on teaching? You should check if you really need it in that country. If your goal is too go to that country and you have to do the cert. then you should do it. If not then spend your time on reading this forum and articles about teaching. That helped me a lot more than a little cert.