After watching The Force Awakens, I pondered Han Solo's approach vector to the planet before exiting hyperspace. For the life of me I can't understand why he aimed directly at the planets surface (90 degree approach) instead of a much more understandable 45 or lower degree vector. Lets say that the shield around the planet was at an equivalent, to earth, maximum atmosphere distance of 300 miles. After exiting hyperspace somewhere between the shield and the planets crust (lets postulate halfway but it seemed a lot closer to the planet than that), 150 miles goes by rather quick, and requires harder maneuvering, when aiming directly at the planet, even at a much lower velocity after exiting hyperspace. So why not lower that entrance vector down to a minimum of 45 degrees to expand the amount of space you have for maneuvers by at least an order of magnitude.
Remember, it's extremely difficult to successfully navigate through hyperspace. Consider Han's line from A New Hope:
Traveling through hyperspace ain't like dusting crops, boy! Without precise calculations we could fly right through a star or bounce too close to a supernova, and that'd end your trip real quick, wouldn't it?
It's entirely possible that there was a very small number of or even only one possible hyperspace route from D'Qar to Starkiller Base at that point in time. Keep in mind that this is not like other examples of hyperspace travel where pilots drop out of lightspeed some distance away from their target and then zero in on it; Han is attempting an interplanetary hole-in-one where if you fail, you die.
With all this in mind, it seems reasonable to me to aim for the center of the planet if possible, thus maximizing your changes of survival if you wind up slightly off target. And seeing as Han is easily able to immediately pull up and fly an easier (well, kinda) trajectory to the ground, it turned out pretty well.