When I was a noob I fell for the overpriced blister pack con. £20 from a guy in the market!
I know there are reputable vendors who stock blister packs and say they're fine, but it seems to me there's no way to tell which, if any, are OK.
Mine actually worked OK. The CE4 was fine (as far as they can be) and the battery worked and within a week it had paid for itself in unsmoked fags, but when I sat on it and broke it, further investigation showed it was no more than a 300mAh battery masquerading as a 900mAh, with the spare space in the casing filled with foam rubber.
Fortunately, in my case the only flaw was the misrepresentation, and it was otherwise properly wired (though the charger packed up early and had to be replaced).
Due to the amount of misrepresented (and sometimes poorly constructed) blister packs, I would advise anyone against buying one.