ATC can be a challenge at times (and not as I'mNotAnEric states, necessarily during emergencies - they are just another flight with a higher priority if handled properly)
However I would like to back notanEric up when he says ATC can often be a piece of p***
The reason it is this way though is because of the selection process and the extensive training that ensues before validation.
I would like to think that anyone who constantly found their job a challenge (in-so-much as difficulty), would be chopped or sent to a less stressful unit... for both their sake and their colleagues and customers!!