It's not as important as the NT but it is still important in that we can more fully understand how the NT is a completion of the OT. It's shows the beauty of God's complexity and depth- how everything in the OT had a deeper meaning than just what it seemed on the surface. For instance, God giving the Isralites manna falling down heaven every day when they were in the desert 40 years. That had a deeper meaning. It was to forshadow how Jesus would come down from heaven to be our daily bread - to feed not our bodies (as the Israelites) but our souls with the Holy Eucharist. Also, there was Abel, the sherperd, was killed by his brother. Abel represents Christ the shepard who was killed by his own. There was Noah's ark, which represents the Catholic Church - the Church was the ark neccessary for salvation just as to enter Noah's ark was necessary to be saved from the flood. Nearly every character in the OT and every occurance has a deeper meaning. With the OT we understand our Catholic faith more fully.