I love this show! Apart from the (I think) vulgarity of the term "thank God", it's such a great show to watch. I really enjoy watching Theatre Sports and it's inspiring to see actors/comedians who are really good at thinking quickly and improvising clever ideas. (Of course sometimes they're not so clever... like Frank Woodley had a bad night last night, that was a bit embarrassing.)
There's such an art to improvisation. And such a fine line between "this is really entertaining" and "what the heck?!" I remember doing impro classes and struggling to find new ideas that developed the story rather than blocking something. Of course the difference with Thank God You're Here is that all of the 'backing' actors know what is happening and have story ideas already planned out, and only the "featured' actor is left wondering what's about to happen. That would make it even harder I think. Often they are expected to finish someone else's sentence and there seems to be only one or two correct possibilities, so when they get it 'wrong' it's fascinating to watch the way they deal with the correction and redirection. Some actors cope well with that, others get all flustered and find it hard to carry on with the flow.
Anyway, I like watching it. I wish there was more of that sort of thing on TV instead of so many silly game shows and ridiculous reality shows.