For a year or so I have been contemplating buying a bicycle seat for our son AJ and was looking for something that would give us piece of mind when we are out as a family on our bikes.
I purchased the Weeride Kangaroo from Amazon @ £64.99 which was a sale price. When it arrived there wasn’t really much to it but I could see how the instructions could easily confuse some people. The bar mounted first between the seat post and frame underneath the handlebars (be careful not to mount it to the handlebar stem or you won’t be able to steer!). The seat then simply screws down with a bolt which can be tightened by hand. My bike is a Giant XTC2 and has a big chunky aluminium frame so the bolts on the front of the bar were not long enough to attach it. Luckily they provide two extra long bolts for such an issue and it was not problem switching them over.
When I took AJ out for a ride around the block I found that his head hit of my chest quite a bit but you get used to it. He seemed to love it and the foot rest buckets seemed to keep is feet in place. It does feel nice and secure as he sits in between you and the bike so there is definitely a pretty low chance of him falling out.
Dismounting takes a bit of getting used to as you need to throw your leg around the back of the bike and over the seat rather than through the centre bar which you can no longer do. I would suggest ensuring your seat height is adjusted so you can put your feet comfortably on the ground while sitting on the seat.