This is a well made show from the creators of Bear in the Big Blue House.  It follows the adventures of Snook (a Giant Sloth), Wartz (a tree frog), Ick (a fish) Burdette (a quetzal bird) Smooch and Winslow (two marmosets who are brother and sister) Madge (a turtle) Bob (an anteater) and Oko (a howler monkey) as they explore, investigate, and learn about their world.

The show takes place in a giant tree in a rainforest, and discusses natural sciences and environmental themes while remaining refreshingly unpreachy.  Typical subjects include healthy eating and living habits (don't eat too many sweets), understanding the limits of your own abilities (There are things you'll never be able to do- such as fly by flapping your arms- and that's okay), responsible stewardship (plant more of a useful kind of tree so it can continue to be useful), and so forth. 

A Big Big World is very well written and it never talks down to kids.  Characters are like real people; able to be petty, or mean, or ignorant just like anyone else; but it's always clear that the bad behavior is not encouraged.  Lessons are imparted without being hammered like a ten penny nail, and the songs are pretty much all ear-worms, so be careful. :)

On a technical level, the show is brilliant.  The puppets are beautiful, and it's refreshing to see someone do a puppet show for kids where the puppets don't look like Muppet knock-offs.  The acting is top notch.

We have all of the episodes available on DVD and our little girl loves them.  Highly recommended.