Vision - I'm rather liking the concept here of a person going down into the sea. Gives off a good feeling of depth in my opinion.
Originality - Reason I give this a 4 is because I've seen concept before more well executed. What is more, the top of this pic seems flat for me, like I feel it couild have a better light source, since he's going down from the surface.
Technique - Some of the points that I mentioned for originality lend themselves to the technique for me, like light source.
Impact - One thing I would do is to make this a different color, not to say green isn't bad, but something like blue would do just fine if you will do that.
There is certainly a theme in this piece of art, a dark theme which really makes the viewer think when looking at the character sinking into the sea. Asking themselves, "what might the key be for?". Are the creatures bringing the character down or trying to push the character up? No matter what the answer; it still is an obviously cold feel to the painting. Like a bad dream.
I was at first surprised by the concept really, the key hanging around the character's neck made the painting much more interesting than it would have been without it. Truly it is uniq by its reflections of darkness when a person begins to consider what they key may be for and what may it symbolize?
As for the technique; the one point that really could be improved is the color; it's very monotone except for the character. Some blue together with the green colors would make a big difference. The light source at the top can also be improved, it does not look like real light. The shadows and darkness with some light at the bottom of the painting is really good though.
This piece of art had quite an impact on me. I began to think and look at it from different perspectives, mostly concerning the key and if the character was drowning or not. Lost in a dream or lost in the real world? The painting would had a much stronger impact on me if the colors were more impressive. Now it feels a little bland unfortunately.
Overall it is a praise worthy piece of art that I consider very well executed.