For the most part as long as they're doing it in a place that it won't be bothering others, such as their home or a designated smoking area, I don't mind.
With that said, I smoke cigarettes. It's a nasty habit I've developed in the past year or so, and yes I'm well aware how awful it is for me. What does gets annoying to me though is when I'm smoking and a vape person starts preaching to me about how they're a superior person to me because they vape instead of smoke. I only smoke in designated smoking areas and throw away my butts because I'm not an asshole. Just leave me alone about it and go about your day.
As someone who smokes cigars on occasion, fuck people who just whip one out in public and start smoking around random people in a crowded area. Cigarette smoke is tangibly worse in every way in my opinion, except cigarettes produce less smoke and take much less time to finish. A cigar can take two hours to finish and produce huge clouds of smoke on every draw, depending on what you're smoking.
Yea it was incredibly rude and just as I was about to sigh in relief that he was finished with his cigar he pulled out another one. I expect cigarette smoke and weed smoke at an out door show but seriously I was thinking of places where that guy could shove his cigar. (he also nearly burned several people)
As Coolpool mentioned, super handy for people who're looking to quit smoking - and sometimes a puff is nice, 'cause they've got ten billion fuckin' flavors. Though it's allegedly more efficient to vape weed than smoke it, I find it's really slow and kind of a pain in the ass, and it seems to me that vapes require more maintenance than pipes or whatever. Also, they're expensive as fuck compared to said other pieces. Put me down for "try, but never buy".
Anyone who says "vape nation", or any variant thereof, unironically is pretty fucking degenerate, by the way.