First Impressions:Color - Crystal clear. More clear than my mixing ingredients or the water from my tap, even
Smell - Watermelon Bubblicious. Exactly perfect dead-ringer for the smell of this gum

Mixed at approximately 70/30 PG/VG, 18mg.
The flavor concentrate doesn't seem to noticeably affect throat hit or vapor production when compared to the base without any flavor
Direct drip on an LR 510 atty, 10% flavor:At 10% flavor, the mixed juice smells just as strongly as the concentrate did by itself, but the flavor is a little gentler on the palette than the aroma first suggests. A hint of "cold watermelon wedge on a hot summer day" flavor was present on the first few vapes, about half-and-half tasting of this and the watermelon bubble-gum/candy flavor that it smells like. Sweet, but not overpowering, initially. Actually quite pleasant since I do enjoy watermelon and spent much of my early youth gnawing on the aforementioned gum.
After a only a few vapes, the fresh watermelon flavor is no longer present, just the candy-ish taste
Direct drip @ 20% flavor:Basically, at this flavor level it tastes pretty much exactly like it smells. Almost too much so for my taste
Note: after dropping back down to 10% flavor, I cannot get that fresh watermelon note in the flavor again. I'm beginning to think that was just my taste buds playing tricks on me
Standard Tank atty (freshly cleaned and vaped through with unflavored juice to clear it fully), 20% flavor:Flavor is a little more subdued in the Tank, but after vaping it for a little while already it's a welcome change. Still exactly like the watermelon Bubblicious gum.
Come the next morning, after my taste buds have had a chance to rest, the taste isn't as sickly-sweet as it got after a couple hours of vaping it last night. I would liken it more to the 10% mix I dripped, initially
Standard Tank atty, 10% flavor:Flavor is only a little more subtle, still very candy-ish. In the Tank, I think I actually liked it a bit stronger. Nearing the end of this tank cart now and it hasn't started to become unpleasantly cloying like it did yesterday.
Overall Impressions:Definitely one of those flavors that's better at a lower level (10-15%). A pleasant vape if you want something sweet and candy-ish. I would definitely vape this flavor again at some point, though not regularly as it does get a little cloying after a while.
If you want a genuine melon taste, you may be disappointed, but if you have a sweet tooth then it will satisfy