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. For example, if you learn about web servers under Linux, you will find that knowledge crosses over and applies to any system in the world.
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).
Working as a system administrator involves many ethical issues that may not be evident at first. As a system administrator you have full control over an organization's computer systems. Recall that almost every item of information passing through your UNIX network will be readable (even modifiable) to you. It is as much your responsibility to not abuse your privileges as it is to keep this information flowing. Implicit in this responsibility is a great deal of trust on the part of both your employer (officers, managers, and owners) and the individual employees who use the systems that you manage.
Employers pay you to maintain their systems in a way that contributes to the success of their organization. Your role also has an important effect on individual users. Although you may be working behind the scenes most of the time (and probably should be if things are running smoothly), remember that your fellow employees cound on your work in order to do theirs. A lack of preparation or accuracy on your part can lead to companywide downtime.
What follows is a small itemized list of general qualities a good system administrator should strive for. These do not pertain specifically to Linux, per se, but are equally important for a wide-variety of system administrative tasks.
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.
Consistency: System administrators often lay down guidelines for their users to operate their systems or obtain technical support. It is very important that they stick with these guidelines and avoid straying from them in "special cases". Straying from the guidelines may have the undesired effect of leading others to think you "play favorites" when it comes to support, or it may set you up for abuse or even impossible expectations from your fellow coworkers.
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.