I know this is one of those books you read growing up and not as an adult (unless you're reading it to a young `un) but I missed out on this and wanted to find out what it was about.
Well, a creature called the Once-ler (you only see his green arms) comes to a verdant land of trees, fruit, and creatures, and begins chopping down trees to make his "thneeds", awful clothes made from the trees' tops. The Lorax appears to warn the Once-ler of the dangers of what he is doing but the Once-ler is making too much money to care. Soon all of trees are gone and so is the wildlife. This once thriving environment is now a desolate wasteland.
I think the message is a fine one - protect our forests! Stop de-logging the Amazon! (it's not really that specific but you get the idea). The only thing I was disappointed by was the Lorax himself (itself?). The Lorax doesn't seem to do anything other than wag his finger and then in the end he disappears. Hmm. Not much of a character is he? Just seems to be a walrus faced gopher who, instead of doing something positive, just seems to want to complain so he has the moral high ground.
Anyway, as with all Dr Seuss books it's got a fun rhyming scheme and a great message so that the book is enjoyable even for a grown-up like me. A kids' book with a conscience - just not a great main character.