Hercules hooks--- do they work??

i just paid out da azz getting my stuff all framed and i want to hang it....i remember my FIRST attempt years ago soo proud hung shelves...and just when i was to put the last of the knick-knacks up...CRASH....everything + chunks of drywall laid in a pile on the floor..LOL..didn't know about studs(of the wall variety ;o) ) way back then......anywho....i do not want to have to go through using a stud finder or tapping...and what if the stud isn't where i want the picture.....anyone use em?....are they really that easy??...and can they hold custom framed investment art???? i cannot afford to trash these frames!!!