Although there are a number of missions, many involving the fire department, the police department or the ambulatory services, missions really boil down to completing the same steps each time: Figure out what vehicles, equipment and personnel you need, send them to the scene, figure out how to use them, and get the mission completed.
There are many different vehicles, including fire trucks, police cars, communication vans, ambulances, and tow trucks, many of which can be equipped with items like fire axes, jaws of life, chainsaws, and other items, and a variety of personnel, including police men, sharp shooters, firemen, emergency doctors, and more. These could have proved interesting if there was some freedom in completing missions, or if the vehicles, equipment and personnel could be used in different ways, but this isn't the case.
And the problem isn't the variety of items in the game, or even the missions, necessarily, but instead it's the fact that there's little suspense or tension. You have to stay within your budget, and there are some time constraints, but one can simply replay a mission until you figure out all of the variables, and then just complete the mission correctly.
And though this is probably true of many games, unlike the best of those, Emergency 2: The Ultimate Fight for Life is not compelling, nor does it help suspend disbelief. It ends up treating the subject matter, which ranges from train wrecks and nuclear meltdowns to hostage situations, tritely. It is unfortunate that a game that probably gets sales from the events of 9/11 doesn't do it any justice.