The metric system is advantageous because it doesn't require conversions or use fractions. There are also fewer units in the metric system, and it uses simpler prefixes. The main disadvantage is having to teach someone who's used to using imperial units how to use the metric system.
The metric system has only one unit for each quantity, so there is no need for conversion. Instead of using fractions, the metric system uses decimals. There are only 20 prefixes to learn in the metric system, and powers of 10 are represented by letter symbols. There are 30 units of the metric system to learn, and many units are used by specialized industries. Because of this, it is easy to memorize a few of the basic units that are commonly seen.