To begin with - It was a nice read and the atmosphere got me right away, altough I hardly like any historical settings. Probably the setting of some well-known elements, like the consume of absinthe or the Belladonna berries, have had a nice effect.
The drawing style was also likeable, although it wasn't outstanding or remarkable in a specific way. It's clean lines and sketchy style matched the whole way of how the story was told. You have your blank spots, which must be accepted considering the length of the Manhwa. Therefore the reduced artwork was somehow just right with this feel in my eyes.
The characters are well developed and after the first chapters, they can be differentiated quite clear. As for me, especially Euan and Ray have been caught my interest. The relationship between the brothers has been nicely put in scene, without touching the line of the cliched boys love scenario. The are different, yet have become close, while facing the hardships bound to their social status and home. The other characters have their nice points, too. Although the main character came off a bit wavering, even though her emotions are stable and understandable.
The plot itself is interesting, but longs just for too much by times. It might have been a good idea, to keep a closer look on the order of things and their meaning. Every now and then, I was asking myself, if such a tragic issue or dramatic feeling can be resolved just like that, while moving on to the next step. The ending was okay, but ...
I agree about the resolving of Euans feelings. It was a matching end, implicated right from the get go, that his easy way with affairs might get him one day, so the death of him isn't my point of critic. It's more, how his feelings for Gabriel just seemed to fade and become another mood swing, after he had a hard time facing her in a non-passionate (or impulsive) manner before. It's clear, why he kind of chooses Ray's well-being before his unrequited love, yet it was somehow weird how he smiled, knowing his brother will be in pain after his doing.
To sum it up, you get a nice read with this Manhwa, but you should consider the depth of the elements involved and the length of it. ^^