Its really good for date manipulation and readability and takes into account all the things like leap years and whatnot. For instance to add a month, you can do
new moment(new Date()).add(1, 'month');
new moment(new Date()).add(1, 'month').endOf('month');
new moment(new Date()).add(1, 'month').startOf('month');
you can add days/months/years.. start of day/month/year etc... You can also do date comparisons
var dateA = new moment(new Date('1/1/2018', 'D/M/YYYY'));
var dateB = new moment(new Date('2/3/2018', 'D/M/YYYY'));
var isSame = dateA.isSame(dateB);
var isSameOrBefore = dataA.isSameOrBefore(dateB);
var isSameOrAfter = dateA.isSameOrAfter(dateB);
There is also, before/after/isbetween etc...
It makes your code easy to understand and you don't have to reinvent the date manipulation wheel or account for a lot of odd things in date manipulation.