I agree with Giordanno's top four. I would add:
5) No associating with "worldly" people
As far as what I like:
1) Training in public speaking
2) Easy to make "friends", if you tow the party line and don't know TTATT
3) Hospitality for those in ASL or other language groups (can easily find a friend to stay with when travelling, feeling of community/camaraderie). I think this is what most of those (like my grandparents) felt in the early days of the org. It's a close-knit community and they really help each other out.
I can't think of any more at this moment, but I'm sure there are a few more.