For one thing, it makes grading much easier. More importantly, it helps you concentrate on the problem solving process and spares you the tedium of performing calculations and unit conversions on your hand calculator. It makes spotting and correcting dimensional inconsistencies much easier. MathCad does require some initial effort to learn.
Many students initially dislike being required to use it for homework.
However, by the end of the semester, most are glad they did and tell me they will use it voluntarily for other courses as well. The version of MathCad we are using is MathCad Pro 2000. There is a built-in tutorial that you should begin working through right away to begin getting a feel for how to set up and edit equations.