IMO, vapes are for affluent hipsters, not hardcore nicotine addicts. I've had several (aborted) attempts at replacing cigs with vapes, and although the idea seems pretty sound, the harsh reality put me right off.
Pros:
Ultra cool and trendy: What can be better than blowing a huge plume of blueberry flavoured vapour directly into the face of any cunt passing within a 50 yard radius?
It will save you money: Theoretically yes; but this is highly debatable - whatever the manufacturers would like you to believe.
It's better for your health: Hmm, again this is debatable. This depends upon so many factors: quality of device and quality of e-liquid. But the one thing that no-one tells you is that any perceived (but not proven) health benefits rely upon regular servicing of your device. Get it wrong and vaping can produce more formaldehyde than regular fags (can't remember source, but it took me 2 minutes to find that out online).
Cons:
Too many fuckin variables - you got to find the right device combined with the right liquid. Generally the more expensive the better. Mr.Z.Bandit is correct in saying to go for the high VG

G liquids and the American ones seem better quality. DONT buy the shit available in Poundland's et al - unless you're just a posing cunt who wants to look hip! Then there's the multitude of settings available on the high end devices - get it wrong and you end up feeling like your throat's been ripped a new arsehole...
Maintenance: This is the biggest con. Suppliers give the impression that the only costs after the (possibly quite significant) initial outlay is the juice. This is bollocks. To keep your device running efficiently, you have to regularly change the heating elements and the mouth pieces. The heating element soon accumulates huge deposits of skanky residue that makes getting a decent lungful virtually impossible; and the mouthpieces are so fuckin fragile that the slightest knock will have your precious e-liquid oozing out onto everything in sight.
Charging: Yet another bastard electronic device to juggle charging time with all your other bastard electronic devices. Once yer battery is dead, yer fucked. No grabbing an ashtray of dimps and rolling a quick n dirty fag...
Refilling: Oh this is fuckin fun!! This shit gets everywhere, and is quite corrosive. Keep it well away from any surface other than pure granite!
Social acceptability: Fuck all. You're still destined to stand outside in the pissing rain chuffing on your rapidly discharging, leaky, overpriced piece of uneccessarily complicated hipster wank fantasy, whilst looking on enviously at all the cunts smoking proper fags.
As you can probably tell, I wasn't particularly enamoured with the whole vaping 'experience' as I found it a total faff with very little benefit. I've tried several devices ranging from an ?80 variable voltage lump of metal to ?10 pen style jobbies. They all have the same disadvantages. Gimme a soggy rollup with no filter any day of the week...