I have a 5 year old and a one and a half year old and both fit in there. My son is pretty tall for a 5 year old and even though his legs can hang out, I asked him if he was comfortable and he said yes. Also it has a little storage thing in the back for drinks and food to take with you. In total I was hauling about 75lbs and even though it sucked the trailer held its own for 15 miles. Very easy to setup and run within 10 minutes or less.
I ordered this to go with a newly acquired bicycle to pull my 4-year-old and 2-year-old grandchildren. They love and are always wanting to go for a ride. It was fairly easy to put together and attach and feels very sturdy.