Unacquainted with any other way, a baby moved from an infant carrier into a rear-facing seat will be perfectly satisfied if not delighted with a new car seat, the latter being bigger and more spacious.
If your child has already used a forward-facing car seat, some dissatisfaction may occur. For the sake of safety, however, keep your child seated in the rear-facing car seat positioned to its maximal limits.
Some children do not like being driven in any car seat. Remember that keeping children in rear-facing car seats increases their chances of surviving a car crash by 5 times.