My son can't get enough of Oobi. The characters speak in the basic broken English that we talk to our children in, and he has learned lots of words and even several abstract concepts from watching the show. About 6 months ago he was jumping on the bed and laughing and said, "SILLY!" I was sure I heard wrong until I saw him watch Oobi for the second time that day and the characters were dancing and laughing and saying "silly." He has that concept down cold now.
This summer he has learned a LOT of language from Oobi. The characters speak in short sentences (Look! Oobi clean room. Now go outside.) so I think it is easier to pick up what they are saying. He has begun using scripted language from the show. When he wants me to quit folding laundry and play with him, he will take it out of my hand, look at me and say, "Game over". When he wants me to join in with him, he will say, "Oobi sing, you sing. You sing." No matter the activity, he uses that sentence.
I also have a theory about their hand 'faces' being less complicated and more easy for him to understand, but who knows.