By far and and away the most common criticism of utilitarianism can be reduced simply to: "I don't like it" or "It doesn't suit my way of thinking". For an example of this, here's something from someone who might prefer to remain nameless.
"Producing the greatest good for the greatest number is fine as long as you are not hurting someone you really love in the process. For instance, with the trolley situation, I would rather kill 5 people on the main track than m mother on the spur track. Utilitarianism runs into problems when sentiment is involved!!"
I suggest one certainly will have a problem if one tries to merely codify one's personal inclinations - and then expects this to hold as a universal standard of right and wrong - however, the problem is not with utility!
Utilitarianism is alleged to be faulty in the way it requires us to think about all kinds of actions - to apply the felicific calculus in disregard to any feared distaste of the result. For example, some issues or potential actions are (to a non-utilitarian) "morally unthinkable":
"Consequentalist rationality, however, and in particular utilitarian rationality, has no such limitations: making the best of a bad job is one of its maxims, and it will have something to say even on the difference between massacring seven million, and massacring seven million and one." 
Utilitarianism does indeed have something to say on this issue - otherwise it would suggest that the life of this extra individual was of no importance. I suggest it as a virtue of utility, that it does not arbitrarily discount value depending on some detail of the situation: all interests count - simply and fairly. The fact that opponents of utilitarianism admit that they won't even consider some situations seems to me to be most damning to their credibility, and indic