I can second this in terms of making a teacher's day. The times I've had alumni tell me they appreciated me as a teacher are special moments.
That said, I have to disagree with the perks comment. I'm contracted to work about 182 days a year. That's 50% of the days in a year or about 16 weeks of vacation for the normal working stiff. Further, my salary used to be embarrassing, but that's changed in recent years. I'm making around $100K now. Yeah, I'm at the end of the pay scale, but I'm thrilled with my salary for what I do.