Yeah it's always that, "popcorn lung" which is so horseshit it's laughable, and studies that burn coils down until they're dry and red hot (figuratively you'd cough so hard your lungs would come out, you'd have other problems like maybe literal burns).
As far as I've seen, some UK studies have shown it's not good for you (which is a strawman, people claim it to be better than cigarettes, not healthy like fucking broccoli. "Good" in terms of harm reduction sure but literally nobody has ever claimed it to be beneficial otherwise), but city air with it's pollution is often worse for you than vapes, so anyone who lives in a moderately large city can STFU, if you live in Unincorporated Loupe Co. Nebraska and have never smoked, maybe you have room to talk shit.
As far as cost goes, if you can homebrew juice in your location it's an absolute game changer. ~$3/60ml.