I agree with some of the other posters. On a day to day basis, the biggest drawback by far is the lack of flexibility in my schedule now and, related to that, disappointing friends and family members who don't really get it. I will not plan any social activities/errands for a weekday because it feels unfair to work all day and then leave the dog alone at night, too. And weekend activities have to be time limited, because again, I don't think it's fair to have a dog and not see it. I don't mind this schedule, but it gets old to have to constantly let friends/family down by declining invitations that conflict with it. I'm pretty sure my in-laws think I need some kind of crazy dog lady intervention.

A drawback that comes up less often but is probably the most stressful part of dog ownership is travel. There have been times when we couldn't find a sitter and so didn't go to wherever we were hoping to go. Sometimes we travel with him if seeing family where dogs are welcome (not always the case) but it's stressful for both us and the pup. E.g. we just had to cancel holiday plans because he's been sick and we didn't want to stress him out further with travel. It sucks sometimes, but it's absolutely worth it IMO.

Wait, one more--the anxiety. I see new posters here all of the time saying that they're considering a dog to help their anxiety, and while I know dogs can certainly help some people, that always sounds so insane to me. I worry about my dog's health and happiness roughly 114 times a day. He had a particularly scary health issue a couple of weeks ago and I felt (err, still feel) like a complete basket case. It can be quite stressful to know you're responsible for the well-being of another life and, at least for me, those moments of heightened stress can result in higher levels of anxiety generally, i.e. not just related to the dog.

Anyway, I know this is long, but I want to repeat that having a dog is absolutely worth it for me. Stressful at times, but worth it.