i haven't had one, but i researched it hard and talked with a bunch of friends and reviewers and they all said... its a great kit for a starter or a beginner or somone who needs a cigarette lookalike... but its not as good as a 510 with a good atty.
I too started off loving 510's and then got to hate it because it was pretty crappy... well... i can tell you that it wasn't the 510 battery, it was that the atties i was using were old, burned dry (i will never ever burnclean an atty again) and they just didn't have the capability to produce any kind of vapour... fast forward to the ego atty... loved it, but again, ruined that by burncleaning and then came onto cartos and my CE2 Carto is not really a carto (ie Vertical atomizer coil) but rather a 510 atty sitting ontop of its own dripping resevoir... the atty stays wet and great tasting and even when almost empty... a quick flip upside down to help the wick bring the last bits of juice to the atty is all that's needed...
i've heard some have issues with them... i've been using one CE2 Carto for almost 2 weeks, beating the hell out of it and taking it apart to do complete pat down to change flavours and its only now starting to show signs of cracks and splitting... but when you get 5 for the price of one regular atty... its a joke... i figure that if i open my next atty and treat it the way that i really would treat any other atty, it will last even longer...
i also got the CE2 cartomizers(only difference is metal tube vs clear tube... only issue i have with it is i never know how much is in it but at the same time, i only have to flip it, try to vape and see if it stops producing to know that i need to refill it... i suspect that the CE2 Cartomizer will last me a very long time...
the flavour from these things is like nothign i've ever tasted in e-cigs... its like its directly dripped onto the atty 24/7 without ever drowning it... all i suggest doing is getting some decent drip tips because the tip that comes with it is crap and you can easilly get juice in your mouth... but i didn't care for the style of them anyways and used my own driptip till i lost it somewhere... now i just use them as is with no tip and they're just fine!!