I have been using e-cigs for 2 weeks and they are working. Things that I have noticed ...
I'm at about two weeks, also.
I was prepared for the need for extra water, so the dry mouth and sore throat is something I can limit, by keeping my water bottle filled. (My doc wanted me to drink more water, anyway. (vs coffee))
I find I'm also coughing up a lot of the junk my throat accumulated, over the years.
Increased appetite -- My sense of smell is slightly recovered, but after decades of heavy smoking, I don't expect overnight results, there.
And (don't hate me), but I've been trying to gain weight. But I haven't really been binge eating.
(I think extra eating is just to keep the mouth occupied when you don't have a cig in it. The PV does that with fewer calories .... depending on your ejuice flavor.

)
From 2-3 packs a day, I found that 24mg wasn't getting it done. I shifted to 36mg, which is pretty much as strong as anyone would want to vape, and that only if you have a high tolerance.
But I only use about 2ml a day.
I could probably use lower concentration if I were to chain vape, but that would just make the dry mouth and sore throat worse.
On safety, you'll hear a lot of gloom and doom from the FDA .... who is heavily funded by the cigarette industry, and stands to lose a lot of tax revenue.
What most MDs will say is that nicotine is about as harmful as caffeine. (Even oxygen is "toxic" at sufficient concentrations.) But that there's not a lot of statistical data yet.
Or, in other words, there's no indication that it's harmful, but they're covering their bases.
Of course, there *is* a point where nicotine becomes harmful, so keep track of your consumption.
(X mg/ml * Y ml/day = X*Y mg/day)
(My 72mg/day *looks* worse than the claimed "20mg per pack" in analogs, but the absorption rate is different.)
The "best e-cig" is .... what ever works best for you.
I'd like to be more specific, but there really are so many choices out there that you just have to find what suits your use and lifestyle.
I started with the full bore eGo-T type B tank system, which would last me 24 hours on one fill/charge.
But the big stack with the 1000mAh battery is a bit awkward to carry around.
I was thinking of trying a 510, but I found that the smaller eGo battery with a cartomizer is much more compact and still lasts me all day, but the carto gives less vapor and TH than the tank.
So you really have to just try one, and make adjustments as you go.
And, even if you splurge on hardware, at first, consider what you were paying for analogs, *every* year.