Expensive, Challenging, Got me to Prague

When considering moving overseas to teach English, I was too nervous to "just wing it" so signed up for the month-long on-site course. Holy flip was it difficult! In a good way. The teachers are really good at demo-ing their instruction style and you're in front of a class by your second week.
However, I would say that you should be prepared. This course is mostly about teaching style and significantly less about grammar or what to teach. You've got to do all that research (for better or worse) by yourself after the course. The only other thing is that the prices are at US tuition rates. That ends up going a lot further in the Czech Republic, so it becomes pretty clear that the course makes good money off you.
If you go, I recommend looking into your own housing (I ended up paying $500 to sleep in what's called a "walk-through").
While I can't ever get that money back, dropping the cash on this program DID get my lazy, scared, cheap ass to commit to the big move. So, I'd say, do it if you can or just buy a plane ticket first and see what happens :)