As we were preparing for a trip to Disney, I had an idea for a way to carry my son around on some sort of backpack frame. He just turned five and is too big / too cool to ride around in a stroller. Fortunately, as I did a little searching, I found this thing. Though a bit pricey, it basically does what it claims.
Pros:
* Lightweight and compact
* Better load distribution and safety than putting child on shoulders
* Far more maneuverable than a stroller (Picture sprinting out of Disney parks post-fireworks. For that, this thing was AWESOME.)
* Gives the kid a great vantage point for parades, fireworks, etc., when you are in a sea of adults.
Cons:
* The child has to stand up. This isn't really as useful as I had hoped when the kid is exhausted. He wanted to sit down, so he still ended up on my shoulders when he was too tired to walk / stand.
* Not always fast / easy to put on - the hooks have what I will call "safety latches" - little indents that make them difficult to accidentally unhook under load. These also make them a bit difficult to deliberately unhook. It works fine with a little practice, but it generally goes best if there's a third person to help with the hookup between the parent / child harnesses.
* 40-60 pounds is a lot to carry around on your shoulders if you're not used to it. Unlike a "frame" backpack that distributes the weight to your hips, this puts all of the weight on your shoulders. After walking about 7 miles through Epcot following my wife's military-precision "touring plan," the kid was feeling pretty good, but I was pretty tired.
* The straps can get tangled and twisted. The bar orientation gets wonky if the straps twist. Still not 100% sure we got it back to where it's supposed to be.
* Safety - Though it's probably safer than just throwing the child on your shoulders, I did worry at various times about what would happen if I lost my footing. With an extra 45 lbs hanging from my upper torso (sometimes squirming excitedly), walking or running on unfamiliar and uneven pavement, the potential for a fall was probably a lot higher than I should be comfortable with. I did try to use care to use handrails, etc., but I think it's a genuine concern. My wife ended up not trying to carry him around at all, partly because of him being too heavy for her, but also because the weight ratios would have been harder for her to balance.
The whole setup got a lot of attention around the park. Both parents and park employees stopped me to comment on what a cool solution it was. I wore the adult harness and bar almost all of the time just out of convenience. I was able to either sit on the bar or flip it up vertically beside me on most of the rides, thereby eliminating the need for me to put take it off and on throughout the day. On total, we found it to be a good purchase, though the requirement that the child always stand turned out to be a bigger deal than we had anticipated. However, if only just for being able to quickly enter and exit the parks I would buy this item again.