To me, buying an attractive front door can improve the appeal of a house by leaps and bounds. That's why I am planning to move the current front door, which came with the house when he bought it, to the side entrance. The door at the side entrance is old and not a good security door, so we'll simply through it away. The current front door is solid and a good door, just a bit dated. It looks like it would have been more at home in the 1970s.
We are going to buy a really nice wooden door for the front entrance and that will help a great deal with the look of the house. After all, the front door is one of the first things people notice about a house.
I haven't really considered how much of a difference exterior door hardware can make in the way a house looks. At least, I hadn't considered it until I was in the store looking at exterior doors and the salesman was suggesting I buy one of the more expensive exterior door handle sets.