Of all of the things that people say to pregnant women, I think this one irritates me the most. "How do you feel?" Partly because it seems to be asked on a continual basis, but also because it's such a stupid question. What do you mean, how do I feel? I feel pregnant. I'm larger than normal, hotter than normal, everything is awkward and uncomfortable and guess what? It was the same last week! There is no need to keep asking. Most of the time there's a deeper intent to the question. They say "How do you feel?" but they mean "Are you in labor yet?" In which case, just ask the question you mean.
Specific questions can also be irritating, but I can tolerate them. Are you still vomiting everyday? (no) is much better than a generic how do you feel? Still having Braxton Hicks? (yes) is better than how do you feel? "How are you doing?" is better because it has more of a "what's new?" connotation.
The only exception to this is when a newly pregnant first timer asks a more advanced pregnant lady. It's also usually followed up by more specific questions and its purpose is actually more for the FTM to predict how SHE will feel than how you are really feeling.