Although it was classified in the same subject as ray shielding and particle shielding, the relativistic shield was not a shield in a traditional sense, as it did not protect the ship from any type of attacks or energies, except perhaps some types of energy generated from hyperspace travel.
There were some curious effects of traveling without relativistic shields, mainly in that time would pass by slower to an observer inside of the ship than to an observer outside the ship. This would mean that, due to special relativity, the ship traveling in hyperspace would move forward in time faster than from the perspective of an outside observer. Relativistic shielding affected the process somehow, forcing the transit of time in the ship to pass normally compared to outside observers. This means that while only 2 hours would pass for the person inside the ship, outside many years could pass.
One famed example was that of Bosbit Matarcher, who gained brief attention on HoloNet News when his relativistic shielding failed and he ended up traveling 190 years forward in time, from 212 BBY to 22 BBY, on what to him was a two-hour trip.