So, I did see it and my daughter tried on at the local Toysrus. Before you drop everything and run to the store, they are more expensive there then here so you got good price. Amazon is giving you a deal.
Now, how do I rate it? I would say it depends what you are looking for. It is one of those cheap economy costumes that you do not spend much on and don't expect much from it either. As far as the esthetics, it is nicely designed but it is not this kind of punch if that is waht you are after.
I have given it five stars because it seem good for the price. I think that it is good for those who don't want to spend a tone for short lived excitement over new princess.
The colors of Merida generally do not complement any complection, except righthesfully so the read head as in the movie by the the simple color science basic rule. Red and green are the complementary colors so that is why you got your green on Ariel that is red headed and so you got your green on Merida. They pulled it bit further and gave us this turquoise blue that is still acceptable within the color rules, yet.. if you have a girl with any other hair color or complection it does not do much for her. It makes a girl look pale and somewhat sucks the beauty of the owner.
My daughter did not like it much. We eventually ended up with the Disney Store Merida costume, that dark green one that is bit more expensive. Do read my review on that one. And she keept the other one as a girl must have a Merida costume. Right?  However let me tell you, she did not even want to wear it for Halloween, she will wear her Limited Edition Snow White costume that she is so proud of and she looks like million dollars in. The Merida costumes, niether of htem do come anywher  near that Limited Edition Snow White costume that is beyond designers quality and it is an art piece in itself
but then agian, I don't suppose I have seen ONE other Disney costume in history of costumes that would come close to it. It is just spectacular. So, back to Meridas, yes, this one is your okay economy costume, not anywher near as horrible as the one we saw today at Tareget's halloween section that looked like the dress was made of one huge ziploc bag. No exaggertion.

There is another costume like this in this color as opposed to dark green kind.. it is made by Disney and sold by disney stores and that one you can tell apart in quality and style. It is easy to recognise it by the front torso - it does not have any pattern on it, it is just plain. So if you see antything flowerish or whatever it is not that one. It is of better quality and naturally comes with higher price tag but it is slightly better stylized I would say. It also has wider sleeve accent. that golden ribbon to finish sleeve  - is wider then in this one.