I received the Fisher Price Aquarium Swing as a gift when my baby was born and I have used it every single day since then. In fact, my 7 month old baby boy is napping in it right next me as I type! I cannot stress enough the absolute necessity this swing has been in my life post-baby.
For the first three months of his life, the Fisher Price Aquarium swing was the only thing he'd sleep in. My son had severe stomach troubles, colic and acid reflux - all of which made sleeping for any length of time nearly impossible. This wonderful swing saved my sanity.
My son is now 7 months old and sleeps in a crib at night, he still takes two naps a day in his swing though and often if he is having a meltdown it is the only thing that can calm him down.
The only con about this item is that it runs on batteries - four 'D' batteries, so if you plan on using it as much as I do, you might as well buy a truckload of batteries now because you'll use them!