Plenty of young snot-nosed junior officers out there too, Im told.

(Constantly reminded of, more like it hehe)
As for how an older person feels just coming in.... well, you may feel a bit younger during Basic, etc... but hitting your trade I doubt that you will find it as great of an issue.
Being an officer doesnt automatically mean you are that much more mature... (one would hope, but).....
*shrug*. Id choose the right career fit first, and then decide if being an officer or an ncm fits that better.
Do you want to be a leader? Do you want to do much less of the actual taskings, and much more paperwork?
Probably best option for you would be to research your careers, say Image Tech... and either call up a PAO (their names and often numbers are on the DND website on PRs) or call a CFRC and ask if you can have a telephone chat with an ImageTech.
You can also ask to speak with a recruiting officer, and get a feel for what their job is...
Or as one of the many on here
