Hi Lorikay. I've vaped many, many of the previous carts (very good), ordered and received a nice stock of premiums, and have using those for several days. The flavors are better - fuller and very tasty (have tried 5) - the vape is fat and lovely, and I've been pulling away very regularly at work all day and am just getting near my second cart of the day.
I've not gotten any duds nor have I heard anyone report a similar experience (we would) - but I'm sure that Steve will quickly replace any such anomalies. You don't need to threaten or anything here, things are really quite open.
The issue with those flavors that have unremovable caps has been addressed in the forum; many of us just use the condom method to top/refill (I immensely prefer that way anyway). You'd have to read about that one if you don't know it - not sure that any of us would know many tips beyond the very basics at all (for any brand) without resourcing the forums.
If you want to know about technical specs regarding the premiums you'd have to read that also, it's been discussed heavily during the past week in here. And I'm sure that someone who's not pooped from a 12 hour workday here will supply you with specific links. It might be a bit much to repeat it all in here just for you, but knowing this extremely helpful group, they just might. I understand that you'd like all of that explained on the website, but improvements at V4L seem to be a constantly evolving process, and now you've found your way here and might consider taking a deep breath and enjoying the good company and ready assistance. There's a reason for the popularity of these products - as fond as I am of the V4L line, for service, goods, attitude of vendor and support, I'm not slavish, and if I found a better one, I'd sadly and pleasantly bid farewell. Not many seem to.
As for how to tell the difference in the experience itself with the premiums, I'd be glad to volunteer for a blindfold test. Piece of cake.
I've tried liquids from other vendors, and some are quite nice, some very awful, and I've borrowed a friend's 501, and I doubt that any of us are unaware of the competition - we're an amiable, helpful and loyal bunch, but like you, we're not going to spend our hard-earned money on a product or a vendor that disappoints us or is overpriced. Overall, I very much prefer V4L (and did even before the great new carts, immensely). Cheers!