but I've worked in a h.s. for umpteen years so here goes.
The good: in most districts you're considered a "teacher" so same pay, benefits, contract, etc; you get a lot of one on one contact with students so it's not you against 30 (or 35 or...); if you like career or personal counselling, it can be very fulfilling. However...
The bad: in some districts (like mine), you might be the only one for the whole school and expected to cover waaaay too many areas for wayyyy to many kids. Every district is different, but our h.s. of 400 students has only one guidance counselor, and he has to deal with personal issues/crises, career guidance, testing, etc. It's like being any other kind of specialist, when $$ gets tight, you're one of the first ones to get cut down or cut altogether.
My cousin is going back for her masters in this, and is really looking forward to it, but plans on doing it in a large, suburban h.s. where she'll have plenty of support.
If you get a chance, ask to "shadow" some local counselors for a few days/week. Reality is the best decision maker!
Terri