Well, I saw it today, and I didn't think it was too bad. For me there weren't any dull moments, and I didn't notice any gross-out/bathroom humor or hip humor (though I did go to the restroom at one point).
The movie was more of a straight adaption than I expected. I expected the storytelling portion to just be as long as one of the segments from Dr. Seuss on the Loose if not shorter, and then make it an adventure to grow a tree and find/team-up with the Lorax.
The only thing I didn't really like, though it's more of a nitpick, is that they showed the Once-Lers face throughout the flashbacks. It's not as bothersome as seeing Dr. Claw's face in the Inspector Gadget movie, but still a bit weird. But somehow I feel it works better to show his face that much in this movie, while not showing the face worked better in the original book and special. But I don't quite like that they made him human... I felt he was an abstract sort of character with a green body in the original. Though just yesterday I wondered if the hands and legs seen in the cartoon were just part of his clothing, despite them not drawing seams where neccessary, but here it appears he wore long green gloves (and for the record in the cartoon we see the bodies of his family during the celebration and there's no lines or seams where the clothing meets the hands).
And in this the Once-Ler is sort of more sympathetic than in the book or special. Sort of like the Grinch in the live-action How the Grinch Stole Christmas, only his family initially doesn't expect him to succeed, and they basically make him break his promise to not chomp trees down, and then turn agaisnt him after the trees run out. At one point the Once-ler promises not to chomp more trees, opting to just have them plucked, until his mother convinces him otherwise... And after they're all gone she acts like that's his fault.
I don't want to give away much more (I may have already given away enough), but is the town in this meant to be the only town in the world? They call it a town, and act as if there are no more trees anywhere... Did the Once-Ler really chomp down all the trees in the world? Are there other populated towns? Does Mr. O'Hare ship his air to other parts of the world?