Software maintenance is:
* **Intellectually complex** - it requires innovation while placing severe constraints on the innovator
* **Technically difficult** - the maintainer must be able to work with a concept and a design and its code all at the same time
* **Unfair** - the maintainer never gets all the things the maintainer needs, such as documentation
* **No-win** - the maintainer only sees people who have problems
* **Dirty work** - the maintainer must work at the grubby level of detailed coding
* **Living in the past** - the code was probably written by someone else before they got good at it
* **Conservative** - the going motto for maintenance is "if it ain't broke, don't fix it"
Software maintenance is pretty complex, challenging stuff.
(From Coding Horror)