An interesting blog post I came across
If you’re looking for a means to help you quit, there’s a tiny bit of evidence that they might help, but that evidence favors placebo e-cigs about as much as tobacco e-cigs. There’s a bit of evidence that e-cigs are better than traditional cigarettes for lung function, although those studies are really small and transient. There’s also some tiny amount of evidence that e-cig smoke changes laboratory values less than the smoke of traditional cigarettes, although the clinical meaning of this is unclear. So it’s hard to get too excited about e-cigs.