Every pediatrician I've met, except one, has been extremely friendly and loved med students. I would guess that at most places you don't have to worry too much about your day-to-day performance on the wards during your peds rotation other than showing up on time and working hard.
However, most people find the peds shelf quite difficult. So if you have a chance to study for and take the FM one (the one that has peds on it; there were two options for the shelf when I did primary care), you will probably get a nice head start.