Usually you try to get a good airflow inside the case. Front low to rear back is the typical one. When you have bit of a underpressure in the case (more fans blowing out) it's slightly cooler, BUT also collects all the dust. Overpressure on the other hand is warmer solution, but not so dusty one. Happy medium would be to have same amount of intake and exhaust fans (also counting in CFM values)
Now you got 2 out (rear and PSU) and 2 in (front & side), so it quite balanced, as long as you keep it suckin air in. Would be quite stupid to put it blow air out, as it would blow out all the cool air that front intake brings.
I've got 2 intake in front, one exthaust in rear and on top, PSU fan, CPU fan, GPU fan and a chipset fan. Don't think I want a side one as well x) (all @ low rmp, or undervolted, don't want loud of course 
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