I used one from when DS3 was 4 months old, and it was great. Not completed flat, but still enough for him. You might want a little soft carrycot in though as it isn't the softest. I'm not 100% sure, but I think the carrycots fit in them as well.
Jayfer, they are the easiest pram to fold, and to unfold you just get the handle and flick it out. No swearing involved