Act-Utilitarianism requires too much. For example, it is essential that each act carried out requires that each action factor in the outcome that will provide the best over-all well-being, which can be difficult, if not impossible.
2. Act-Utilitarianism requires too much impartiality. To expand further, as we have learned, it is very difficult for humans to be impartial. Suppose five children plus your child are in danger, you can either save your child plus two children or save all of the children except for your own. The normal human response would be to save your child. However, that would not maximize the well-being of all of the adults involved and would violate Act Utilitarianism.
3. Act-Utilitarianism ignores the distribution of happiness. This criticism is pretty much forthright and does not require further explanation. Happiness, rather than being divided is unbalanced. While more people are happy, some could be extremely miserable and heavily affected.
4. Act Utilitarianism ignores duties- Basically, this criticism portrays the fact that one person who is sick and needs to be driven to the hospital in order to save their live could be blown off in order for an individual to work in a soup kitchen and potentially help