Well, I've heard it all now......within some parenting circles, sit-in activity centres like this one are now known as THE RING OF NEGLECT!
It was a godsend for reflux babies when these came on the market.....somewhere safe to actually put your little one down but still keeping them upright....bliss!
From a paediatric physiotherapy perspective they are fine in short bursts as long as the child isn't tip toeing, leaning to one side etc and as long as they get time to develop their floor skills also! Suppose it's just like anything else when used sensibly there's no issue!!
I just think it's another example of parenting gone mad, under the ethos that we are supposed to dance attendance on our little ones all day and all night, 24/7 !!