I'll chime in with some information I got from "Modern Marvel's" on the History channel regarding cigarettes. When a cigarette is made, part of the "tobacco" in a cigarette is actually paper laden with a
juice sprayed on it formed by steeping tobacco in water (like tea), then it is drained off into a second vat, and other "ingredients" are added, one of which is urea (or ammonia).
Ammonia is used in the production of a white powder related to the coca plant (forum wouldn't let me put the actual name) to release the bonds between the molecules in order to render its "free-base" form, the same is true for nicotine in cigarettes. In a PV, the nicotine is still bonded together in globs, instead of in its free-base form, so it takes longer for the body to break it down and absorb it. This will result in a different feeling of a nicotine "high" than from smoking an analog.
Also, because of the fact that your body does not absorb the nicotine instantly, like an analog, you will puff more on your PV in order to get that satisfied feeling. I, too, sometimes get a slight dizzy feeling, and I'm a 1.5pad smoker (pall mall reds).
Note: I still have yet to completely eliminate analogs, but the PV helps tremendously.