I have read in some reviews that the seat is not comfy and that babies keep leaning towards the sides. Is this accurate? Are all the seat positions comfortable with enough support?
Well, you are right, the seat is definitely on the slanted side, as most ultracompact seats are. It is a price to pay for the very very small folded size, along with other small discomforts (read more about ultra compacts and their non-suitability for everyday regular use here). For occasional use, it is just fine, and there are of course better strollers in terms of the upright seat, but I would not put a small baby in this stroller for many hours a day every day, nor would I use it with a baby that did not sit up by itself yet.