Fortunately, R. assembled it.
T. was instantly fascinated and spent a good chunk of the evening (a) interfering with R.'s efforts to finish assembling it and adjust the seat to the right height (so he can sit but have his feet flat on the ground) and (b) riding it in circles around the house.
Even slacker-mama that I am (I'll bring the Little Tikes rideon upstairs to play on if he asks; R. _hates_ this and he has a good point. It would be Very Bad if he fell down the stairs), I will not let him take this sucker upstairs. He tried, but didn't persist.
Very cute. Totally lost it after a while, he was so tired. But a hugely successful toy. You could _see_ him go from just assuming he could lean to the side, like on the trike, to Not Doing That Any More. There really is nothing quite so cool as nailing the developmentally appropriate toy. Usually, I hand him something that frustrates the heck out of him and he screams a lot. Not this time.
Happy Birthday, T.! Can't wait to see what you do with it on the driveway, where his trike and the rideon are favorites to go up the slight hill of the driveway and coast down. I wonder if he'll be able to balance on this thing with his feet up?