I've been using this about 3-4 mornings per week for a little over a month to transport our elderly, arthritic border collie mix to some of his favorite spots that are just a bit too far away for a 13 year old dog to walk. Here's how it's worked out for us:
Pros:
-Very good value!
-Well thought out construction and fairly fast to assemble and flatten.*
-Has allowed our old pup to have greater enrichment without having to go through all of the physical stress
-Seems pretty safe! We had a wipe out on our first journey (hit an oyster shell on the bike path. it was very much like Mario Kart), and the trailer kept him safe and injury free....But also, definitely comply with the recommendation to not exceed 10 or 15 mph! The shell wouldn't have been enough to flip us if I hadn't lost track of how fast I was going.