I love Sesame St. I watched it as a child and I love that 2 people who were on it back then are now married and still on it. I love that they use famous people that I like (Will Arnett for one) and I love that they did Law & Order - that was hilarious!
I love Seasame Street and my kids do too. It's educational and has enough going on that it's not boring for adults if you end up watching it with your kids. I also love that it shows a bit of ethnic diversity and often explains some fairly serious topics in ways that kids can understand (disability, adoption, breastfeeding, and I hear that the South African version has a muppet with AIDS for all the kids over there with AIDS to relate to).
Yes, it is American, but it's not going to change kids' pronounciation if they hear things said differently the rest of the time.
I once read a thread on STFU Parents where a woman took exception to there being an Indian woman on Seasame Street having a nose ring, which for some reason they thought was a terrible influence on children. You can't please all of the people all of the time.
My 2 children grew up witn Sesame St. and loved it, and my Grandsons also watched when they were younger and they loved it. It was never violent, covered a broad spectrum of issues and always entertaining.
When I was a child my mother never let me watch it, because it was so Americanised. However, as an adult, on the rare occasions I've watched it I'm quite impressed by how creatively it's been presented.