are baby rockers really helpful in putting baby to sleep? is this gear really necessary or just a waste of money?

We bought a rocker thinking it would solve our sleep problems - it worked in a way that when baby fell asleep in the car and we'd transfer her to the rocker (as opposed to the crib), she'd stay asleep. But since you can't leave a baby asleep in a rocker for long hours, we'd have to transfer her to the bed when she was in deeper sleep - which didn't always work. So it helped us buy time to prepare ourselves for bed after getting home with a baby who fell asleep in the car, but I think it depends on temperament as our baby didn't like being strapped into it so we never really got to use it as something to help her fall asleep.