My wife had hers removed many years ago.

The main thing the gall bladder does is causes the bile to bolus when fats are eaten. It stores up the bile that the liver makes and when you eat fatty foods it squeezes and puts out a larger amount of bile which helps the fats to break up so they can be digested easier or better. The bile acts as a surfactant. 

When you remove it the bolus effect is no longer there. The liver continues to make bile like before but instead of it coming out in larger amounts as needed it just dribbles out continuously. So eating larger amounts of fatty foods all at once can be problematic. It is for my wife. She can eat the fats. Just not a huge amount at a time or it becomes a bathroom problem. A problem in that she needs one in an urgent way.

We have been told by the medical and nutritional industry for 50 years to avoid fats. They will kill you with heart disease. Well now we find out that is not really true at all and in fact essential fats are a healthy part of our diet. The fact that we have tried to eat low fat stuff for so long may have actually added to  the problem of gall stones and gall bladder problems. If a person hardly ever eats any fat, the gall bladder has little reason to contract. So the bile just kind of sits there in the bladder instead of being squeezed out regularly. Sitting there lets the bile thicken and eventually let the solids drop out forming stones. 

When my wife had her first gall bladder attack we were in Bonaire and had eaten at a Chinese restaurant. Of course we had been following the low fat craze like everyone else because that was what was popular on the shelves of the grocery stores. Everything advertised "low fat". Spent the night in the hospital thinking it was a heart problem, although when they hooked her up to the EKG could see no problem.

Anyway, a long story being kept shorter eventually at home doctor told her was probably gall bladder and back then they thought the gall bladder had no good reason to have one so take it out. And on the advice of her doctor and a surgeon she did. It had stones in it and when she ate too much fat at once it would try to do its job and squeeze and the stones would give her pain with the danger of one becoming dislodged and plugging up her bile duct and becoming dangerous of infection.

Knowing what we know now, first of all we would never have went with the low fat craze. But second of all she would probably not jumped so fast at having it removed. Come to find out, it does actually have some useful function. She might have tried some other remedies before deciding to have it removed. It wasn't a life threatening thing at the time and as long as she kept her diet fat content managed she did not have additional problems or attacks. It was a few months after that first attack before it was finally figured out what the problem was and decided to remove it.

Kind of like tonsils is little kids. The medical community is "hey, maybe those things do actually have a purpose!"

But everybody has to make their own decision and evaluate the severity of the problem at hand. A stone getting dislodged and stuck in the tube and becoming infected is no joking problem. I had that happen with my kidneys and kidney stones and it was no fun.