Rock n play question!

AACaHa13

Hi ladies! DH and I are going to start our registry the first week of April so we've been checking out items. I want to have the baby in the room for at least the first few months. I saw the rock n play and it seems like a space saver and has good reviews. Anyone have experience with it? I guess my question is does the baby sleep flat in it? I thought the baby was supposed to sleep flat and on its back? From the pictures it doesn't look like the baby is flat.... Ftm here lol