Compared to the other types of technical work demanded of a system administrator, learning about Linux is especially rewarding. Whereas some technical topics relate to mastering a specific graphical tool or proprietary method, knowledge that you gain about Linux is generally applicable to a wide range of systems and situations. Although learning Linux well can be a challenge, that knowledge carries over to other systems.
An aside: I personally do not think that learning about Linux administration is as difficult as learning about system administration in the Windows world. I have done both, and can honestly say that Linux does not throw me as many "curve-balls" as Windows. Additionally, Linux has the advantage of having a strong and thriving community surrounding it willing to lend many helping hands. This community's only requirement is "RTFM" (more on this later).
Ethics
See also page 236 of Unix02_Book.
Reliability: As systems administrator, your employer and fellow employees rely upon you to maintain their systems and network. In todays computerized workplace any downtime whatsoever can cost your employer money and inconvenience your coworkers.
Responsibility: As administrator over specific computers you will have access to confidential and/or private files. Unless a systems administartor is responsible, there is a great deal of potential for abuse: Personal and professional e-mail is easily accessible, personal records may be alterable, files may be deliberately erased, security measures may be neglected, data or information could be falsified.
See suggested rules on page 236 of Unix02_Book. Use the "golden rule" (don't do to someone else what you wouldn't want done to you ;-) and keep privacy and confidentiallity concerns ever present in your mind.
