I am a resident and very happy with my choice. I would bet I will continue to be happy.
Some anesthesiologists are going to be miserable, and others will be very content and satisfied. To me, the degree of happiness is not necessarily purely indicative of the job potential, but more of a reflection of the individual anesthesiologist's overall personality and outlook. Just like any job.
If someone is a Debbie-downer, woe is me type, chances are they will hate their profession. If someone is a glass half-full, count your blessings type, chances are that they will appreciate every day they have the privilege to go work in an exciting field like anesthesiology.
I'm young, but that's just my .02. My Old Man is an accountant. I have friends that are CPAs that b*tch everyday about work, yet my father thinks it's the best decision he every made. So, Lesson 1: It's all PERSPECTIVE.
Point being, know thyself. Some people on here act like they have it so bad in anesthesia, but they very well could not realize that they are a 'grass is greener' type and would be griping on the other side of things if they went down a different tract. So, Lesson 2: Some people just like to b*tch. Don't listen to them.
Take those two lessons. Count your blessings. Be honest with yourself. Are you interested in the science and physiology involved? Do you like the amount of patient contact? Could you see yourself doing it?
Make sure you go into it for the right reasons, with the proper perspective. Work hard and take pride in what you do. Everything else will fall into place.