Just remember the weights of the kids that will be playing on this. There is no adjustment so you will need to have fairly equal weighted children on each end. Also, make sure the kids keep their legs out from under it when they go down. My son's leg got smashed and left a pretty nasty bruise. It only happened once, though! Other than that, the kids just love this thing. They are on it more than the swings and slide...and that it saying a lot!
This is a wonderful outdoor toy, but definitely not suitable for a 3 and 4 year old child as the description indicates for the age group. This is suitable for older children who are able to get off the ride one at a time without sending the other child flying off. It seems to me that the middle shaft piece should be able to adjust down in size to accommodate younger children. I tried giving this feedback to the manufacturer directly and they were actually rude. If your child is under 5, I would wait on this purchase. It has now found a place in my garage for a few years... :(