I use mine all the time. I have a shorter almost 5 year old and she has been on it for about 4 months. We love it! You just have to get the hang of tilting it over when they dismount and just giving them cues on what you are about to do.
We have the single burley trailer attached to the trail-a-bike so it is a triple train. We take it to the grocery store, soccer practice and soccer games. The girls love it! I did attach two long neon flags to the trail-a-bike and to the Burley so we get noticed.

If you are purchasing one I would recommend buying either an Adams brand or Trek. The cheaper ones you get at Target (Schwinn) are not as sturdy and harder to find replacement parts for. Craigslist is a great way to find one. They don't get abused like normal kids bikes and are usually in almost new condition.
Have fun!!!