Fewer students apply for this period as it doesn’t follow the typical European school year so fewer students will be in the Orientation allowing for closer relationships with professors and more personalised Orientation.
It allows you to spend a semester working in your home country to put money on the side to help pay for your studies.
This changes nothing in terms of quality of education and you will not be a semester behind if you choose to study in January as each semester is independent from the other .