Some of the reasons for the wide variety of opinions
1. People were different kinds of smokers. I was a 1.5+ PAD lights and ultralights smoker and I smoked slow and savored it. My boss sucks down a Marlboro Red in 3 huge drags. Obviously we have different needs.
2. People have different needs depending on their job and other factors. I have a short trip to work and work at a desk where I can vape and charge batteries and fill carts. Someone else might work under a car. Somebody else might drive a truck. Somebody might want or need the ultra convenience of prefilled cartos and may even have no desire or physical ability to refill them.
3. This board is a bit Ego/Riva/mod-centric and there are some people here who will dismiss anything smaller or less powerful as garbage. Take it with a grain of salt. I would say in general, there is little to recommend a super-minis with their short battery life (something the size of a king cigarette) though 2 of the better models are covered in the multipart guide in the Library here. There are some nice models in minis (size of a 110-120 cigarette, some a bit thicker, some longer). And if you're a heavy smoker of full-strengths or need really long battery life (longer than 3-4 hours) then look larger.
Bottom line though - they are better than smoking. Not just better for you but actually more enjoyable IMO.
One truth to know - other than some hand-tooled units and mods, all e-cigarettes are made by a handful of Chinese companies and are available at reasonable prices (by reasonable, I mean a battery should not cost more than $15, maybe $18 for a special color). Then a bunch of money-grubbing resellers also take both good and bad models, rebrand them, maybe in a special color scheme or logo, and sell them on a spiffy named website or in mall kiosks at higher prices, often with ridiculous prices for replacement parts (like $50 for a battery). A lot of people buy their first from places like that then come here trying to figure out what model it really is and where they can get cheaper parts, and sometimes it cannot be identified. So do yourself a favor and know what model you are really buying,and don't pay too much for it.
The more questions asked, the better off you'll be. Especially if you have a cigar-smoker friend, or an Ultra-Light smoker friend... all of those factors play important roles of finding the right PV for each individual friend 
