The effect of apartment complexes on SFRs in same area

Does anyone have any insight into the effect of apartment complexes on rent prices and ability to rent SFH in the same town or area of city? More specifically there are complexes of 30-40 buildings (each having 6 units) about 1/2 to 1 mile from some potential SFH investments. I guess I'm asking a few things; 1>) is it better to stay away from these areas where there is a high concentration of apartments? 2) does the existence of these apartments mean there should be ample rental business? 3)do you find it hard to rent a SFH when so many 2 bed apartments are cheaper and in same area?