Deadly sin is, well, sinfully delicious...

A very good vape if you like sweet flavors to be fairly potent. I can see SteelerFan's thoughts about it having a notable 'yellow cake' flavor (think of a good, slightly buttery vanilla cake), especially when it's fresh.
I know everyone's different, however, so I'll give you my opinions on my fave GLV flavors (Deadly Sin and El Kamino). For informational purposes, these both have 18mg of nicotine and are vaped in a Russian full size RBA, with the airflow at about 2/3 open (it's cold here in WHYoming...

), using a 2Ω vertical micro coil and cotton wick on an iTaste MVP 2 at 3.6V.
Deadly Sin
Deadly Sin, when vaped fresh from the bottle, has a buttery sweetness, not too definable, but very slightly hinting at a buttery Rice Crispy treat, with an undertone of cinnamon roll and the aforementioned cake flavor, both of which are present in approximately the same percentages for both inhale and exhale. The aftertaste is about the same as the inhale/exhale flavors, and is relatively short lived (about 15-20 seconds), and is not 'clingy' in taste or feel. After about 5 - 6 days of steeping, the flavor profile changes a bit, still sweet, but with some added complexity. The first flavor notes on the inhale a more fully developed, with the forenote the buttery, marshmallow sweetness of a well made Rice Crispy treat, with a notable undertone of a cinnamon roll with a vanilla glaze that's neither overpowering nor overdone. The 'mouthfeel' of the vape is quite good, not 'dry' nor 'oversaturated'. Upon exhale -- through the mouth and nose for me (nigh unbreakable habit from my 'analog' days, lol) -- the flavors reverse, with the cinnamon roll taking the fore, but the vanilla flavor 'sinking' a bit to somewhere between being a forenote and undertone, while the Rice Crispy flavor takes on the role of the undertone. Both flavors mix together very, very well in both cases. In addition, on the finish of the exhale, there's a very subtle, very smooth tobacco flavor, not objectionable in any way, and meshes very well with the other flavors. The steeped vape's aftertaste dwells nicely, upwards of 30 seconds, and is again not clingy in taste or feel. The 'mouthfeel of the vape is the same as when it's fresh. Vapor is fairly thick, and the throat hit is solid and quite satisfying. This is not a vape for being subtle, as the aroma lingers around after the vape, though it is a sweet, bakery aroma and so far, no one's objected to it.
El Kamino
El Kamino is definitely a 'must steep' flavor, at least in my opinion. When fresh, it's an alright vape, but far from matured enough for thorough enjoyment. The initial inhale and exhale flavor notes are that of a strong, chocolate flavor, similar to, but 'darker' than, a Tootsie Roll candy, along side -- and competing with -- a just shy of overly-sweet honey graham cracker with a distinct. There is also a noticeable, but quite subdued, somewhat smooth tobacco flavor and a slight, almost medicinal alcohol flavor just notable on the finish of both the inhale and exhale. The mouthfeel was clingy, but not really objectionable. My first time out with El Kamino I tried it again at a week, and while there was an improved melding of flavor, it wasn't quite matured, IMO.
After just shy of two weeks, El Kamino had come into its own, flavor wise. The chocolate and honey graham cracker flavors were still prominent, but work together beautifully. The forenote was definitely the chocolate, but not nearly as 'candyish' as before. It's more of a dark chocolate (as in a semi-sweet, 70% or 80% cocoa, 'gourmet' chocolate bar), striking the palate as that kind of dark chocolate always does, but in a smoother, almost silky fashion. Following right on its heels was the honey graham, honey aspect of the being far more subtle, taking the harsher edges off of the dark chocolate -- thus making the chocolate flavor's delivery even silkier -- while introducing and subtly co-mingling the graham cracker's flavor as a pleasant, distinct undertone with hints of a nice, older brandy or cognac. After those flavors have established in the mouth, the tobacco flavor flows easily across the palate; it's a rich and nutty, yet smooth and mild mannered tobacco flavor, with slight 'woody' hints. The tobacco meshes nicely with the chocolate and honey graham flavors, and as it establishes its presence in the palate, it brings the brandy/cognac -- that was only hinted at up to this point -- forward, to where it sits just below the honey graham flavor in prominence. The exhale is much the same as the inhale, although the tobacco takes center stage; that said, the chocolate and honey graham notes do not become undertones, but serve as a thoroughly blended, delicious flavor that provides a perfect accompaniment to the tobacco's stronger presence. By this point in the vape, the brandy/cognac is a notable, and quite complementary, undertone that adds to the whole. The aftertaste is quite long, lasting for 45 seconds and upwards of a minute. Unlike the fresh liquid, the 'mouthfeel' it is no longer 'clingy', but rather pleasant. The vapor lingers in the air and is quite copious. The throat hit is very solid, quite satisfying. As with Deadly Sin, this isn't a subtle vape; the aroma lingers in the air long after the vapor dissipates, and while it smells mostly of chocolate and subtly of the honey graham, the tobacco is notable, as well, smelling like some of the better, and in my experience, 'less objectionable' pipe tobaccos.
All in all, both of them are very good vapes, at least in my opinion, and both reside smack dab in the middle of my flavor profile. I hope that my review is helpful for anyone interested in Deadly Sin or El Kamino, and wasn't too wordy or pretentious...
At any rate, keep on vaping, everyone!
-Laters...!
kgs-wy