Much of the inner meaning of the mezuzah is rooted in kabbalistic concepts and personal anecdotes. On the simplest level, the affixed mezuzah serves as a reminder of the Biblical message and its contents. On a deeper level, it serves to raise the spiritual “value” of the home, as the physical structure is an ongoing fulfillment of a mitzvah.
The kabbalists maintain that the mezuzah “protects” the home and the people who dwell therein from spiritual and physical harm. Some people check their mezuzahs when they experience misfortune or illness to see if the writing conforms to the law. A cracked letter, which may be caused by time or the elements (or a cracked or missing letter that was overlooked in the original writing) are flaws which invalidate a mezuzah, and the mezuzah must be repaired. Until the repair is completed, the commandment is not being fulfilled.
An actual mezuzah parchment is not inexpensive since it must be written by hand and is labor intensive. There are many beautifully designed cases that one can purchase to protect the scroll. Decorating a doorway with a mezuzah is a relatively painless endeavor worth all the “mitzvah points” that constantly accrue. It serves as a proud sign and symbol of a Jewish home. Go for it!