Honestly? Most of the time it made us crazy. There was always some kind of "drive" or "sale" going on. It was a lot to keep track of and monitor deadlines.
Some of the help was truly "helpful". We had a whole PTA committee that did "classroom support"- they would literally have a rotation and we knew we could leave things to be copied/cut/glued/laminated, etc. This was especially helpful as our aid time was reduced.
The thing that irritated me the most (as someone who was observing the teacher doing a lesson) was when the PTA rep would just walk in and out of classrooms to collect things as though that didn't disrupt the instruction! I had to meet with the PTA president at O. point and come up with a system to have things in folders outside of the doors b/c it was really disruptive.
These are well-intentioned folks who want the best for their kids, but sometimes need a little reminding that school is about learning and that the extras need to come at times that are not disruptive!