Okay, I'll start off by saying this is a rather clean, eye catching picture, and is well done for the most part- you obviously have lots of talent and potential!
I'll start off with the good-I do very so like the way her mouth and lower lip is shaped, and you used a very nice, impacting eye style that adds uniqueness, and the colors go well together too, although the head could be a bit...shorter? Smaller? The way it's shaped seems a bit off too but that's probably just me! Also the location and size of the ear seems a bit off, and I would have made her shoulders a bit broader, although you weren't too far off c:
also, the way the hair looks flowing is nice, but loose strands would help, also the shading and highlighting seems a little...plain? Like you can clearly see where the brush stroke begins and ends. A bit more detail/maybe some blurring on that would've brought it all together, although it's not bad!
I also like the background, I dunno if you made it or not but the clouds look really nice.
Overall, good job! n_n

Okay, I'm going to break down the Critique in a few sections:

Technique
To begin, there's obvious talent here. The eyes are absolutely beautifully done, and are very enticing...making it the center focus on the picture. The face has a nice shape, although the head could be a tad bit shorter. As for the lips, the soft brushing upon them gives off a nice effect, allowing them to be subtle, and natural looking. The ear poking out of her hair on the right side of the picture is a bit small (in comparison to the head). In height, it is perfect, but in width, it could be a little thicker. Next time, I recommend allowing it to poke out a little more. The body is a bit on the small side. It is about equal to the head, when it needs to be about a few centimeters larger on each side, depending on the view size. The hair flows rather naturally, which is a great appeal, although I suggest next time to have a few free strands, for it will give your picture even more of a natural feel! Over all, I give technique four stars, simply because there are a few proportion errors.

Coloring/Shading/Lighting
The shading on the clothing of this art piece is well done! It reflects several shades when shaded, as well as several lighted areas. This gives the clothing a very realistic feel. The shading and lighting on the bow is dynamic and absolutely beautiful! There is no better way to shade the ribbon on her head! As for the skin, I would suggest using a blur tool to soften the skin shading, as to give it more of a round and soft feel, since flesh has a lot of curves, as well as shades. As for the hair, I also suggest using the blur tool to soften the shading in the hair as well. Also, I would recommend using smaller brushes to define more strands of hair. This would create a more detailed look to the hair, producing a more detailed piece.

Originality
Obviously, your reference you used was of Haruhi, and a scene from the anime, so it does take away some of the originality. However, the eyes are vastly different, causing the piece to glow with portions of originality. For Originality, I give three stars!

Impact
The largest impact upon this picture is definitely the eyes, and how they contrast with the background. The eyes appear to have great depth due to the quantity and various shine types in the eyes. The long lashes also add eloquence to the picture. The contrast between the eyes and background causes the eyes to stand out boldly against the background, which, since I consider them to be the main focus of the picture, is what every artist strives for. For this, I give Impact four and a half stars!

Vision
The quality of the art is very clear, although there are small anatomy issues. Judging by the amount of shading included within the work, anyone can tell the artist has placed a great amount of time and consideration into the work. Yet again, the definite strong points of the work are the way the bow is colored, as well as the eyes. For the Vision of the work as a whole, I give four stars!