Vision: For the sake of this critique, I considered vision the communication of ideas through visual means, such as character body language and symbolism. I think the expressions and body language of the characters do a fantastic job of communicating the relationship between these characters and what's happening in the scene. There isn't anything too concrete or symbolic that I can tell of, but that isn't necessary in this work.
Originality: Because this is a commission, I can't fully speak on the originality of this work. I rated it average because the scene isn't too unique and the aspect of character design is absent due to the design not being yours. The main thing "lacking" in originality is the cliched elements, like the sunset, which are cliches because they work and audiences like them. Also, the composition is fairly generic, but, again, it works for what you're doing.
Technique: Overall, I think the execution of this work is good. I think you did a good job on lighting. The shading makes sense for the position of the light source, and the highlighting improves the shading and contrast. I love the expressions and the upperbody poses, which are adorable and do a good job of communicating what's happening in the scene. The coloring is fantastic and fits the lighting well. The work is a bit messy, but that works with the style you draw with. The biggest flaw is the hand, which is the bane of pretty much every artist on the planet. The hand is a big too long and thin.
Impact: For the sake of this critique, I consider impact made up of two elements. The first element is the emotional impact of the work. The second element is the deeper meaning of the work and how the work makes the audience think or act. The work does a fantastic job of the first element. The sunset and stars are beautiful and set a romantic tone. The subtle interaction between the characters only contributes to that tone. The soft shading also aids in the overall soft, romantic feeling of the entire work. However, the work lacks in the second element. There is nothing wrong with this, and your work is strong in most of what it is trying to do.