We bought our 28 month old son a Specialized Hotwalk last week, and I was a bit concerned because although he liked it a lot, he refused to ride it, he would only push it. But then it was suggested that I show him some videos of toddlers riding on YouTube, which I did, and that made him start to actually ride it in our house. With the rain finally breaking for a little today, we took it outside, and I think he did pretty good.
It was mostly just him gently walking along, but a few times the ground declined and he felt himself coast and giggled. And once he took it down a small grass embankment and fell, but laughed and got right back on.
It's sort of agonizing to watch him plod along, I want to see him start shredding, I must be patient 
http://youtu.be/9MtC5w31sw4