Anosmia is a total lack of the sense of smell. With the lack of smell, taste suffers as well. Most of what we call "taste" is actually the odor of food. To someone who suffers from anosmia, each meal would taste as if a normal person was tasting it with a very bad cold. There is only the sensation of sweet, sour, bitter, and salty, as well as the texture of food.
I have suffered from anosmia from birth. There is no cure for anosmia, I will always lack a sense of smell. From the faint odor of perfume in the air, to the heavy musk of a skunk, it all smells (or doesn't smell) the same to me.
For the senses, I'd rather lack smell then sight, hearing, or touch. Taste seems linked to smell, even if it should be possible to have a sense of smell and lack the taste receptors for sour/sweet/bitter/salty, I am assuming that food would taste more normal to someone who only lacks the sense of taste then someone who lacks the sense of smell. Anosmia is probably the best sense to lack if you have to lack one. Its possible to live a fairly normal life without smell. It is also an easy disability to hide. Most people who know me don't know I lack a sense of smell. When I need to, the words "my sinuses are stuffed up" or "my sense of smell isn't that great" is an excellent excuse.
Not to say that there aren't serious health risks. Natural gas scares me. I know I will not smell any gas leak, thus, I will not live alone in a place that is heated by natural gas. I also harbor the perpetual fear of accidentally eating stale food. I can not tell by smell alone if the meat is bad, or if the milk is too old. Food poisoning is a real risk for someone who suffers from anosmia. There are other problems. If a drain pipe breaks and starts leaking raw sewage in the walls, I won't detect by smell alone. If a pet leaves a "present" somewhere in the house, if I don't see it, I won't know.
There are the social problems as well. I wonder about my B.O. alot. (My girlfriend assures me that I smell fine when I ask her.) I don't trust myself to wear cologne. Any guests to my house might enter a dwelling that seems fine to me but has a hideous odor to them. I will never, ever tell by smell alone that I have stepped in dog poop.
I also have regrets. I miss never being able to smell a rose, a good meal, or the scent of a forest. I can't appreciate any perfume my girlfriend might put on when we go out. I will never know the scent of her hair, or the faint smell of her skin. That's the impossible knowledge that I would want to have.