I hesitated to let my sons watch Oobi for the longest time because of the basic speech involved. However, my oldest son has Pervastive Developmental Disorder (broad spectrum autism) and a speech delay. Watching Oobi has expanded his vocabulary tenfold. He can recite entire scenes now, and is learning to put words together. It works for him because it takes out articles, contractions and superfluous words and gets down to the basic words needed to convey meaning. The "extra" words were bogging down his understanding. So, while I agree that the speech in Oobi isn't good for toddlers who are talking at or above age level, for those struggling to learn, it could be a valuable tool!
In addition, the show is DARLING! Even the adults in my house love to watch it! You actually forget while you're watching it that they're just HANDS with plastic eyeballs! The episode when the kids put on a production of Little Red Riding Hood is SO entertaining. It's even taught my kids to start singing!