I like the expression on her face. Gives the photo quite a punch. The colour is also nice - nice hues of blue to contrast the yellow of the daisy. The background also brings out her eyes brilliantly.
The tilt of the hat and the imperfection of the daisy work beautifully in conjunction with the symmetry elsewhere throughout the photo. Very eye-grabbing shot.
I've been learning recently how to control light and make my own directional light filters, so I found this picture to be an excellent example of what can be done with such things. This is really fantastic.
The only thing that I can say I don't like would be that the eyes (and indeed some of the rest of the face) look like they could use a bit more sharpening and possibly working the whites of the eyes by just the tiniest bit.
In response to your request for comment: This is a great picture, lots of fun. The lighting behind the subject's head is pretty much perfect for this shot, bringing out the beautiful discs of her irises, and reflecting the almost mandala-like repetition of the circles in her eyes, the flower, and the pendant. So it's very nicely balanced, as, ironically, not all perfectly centred pictures are.
It's only my personal taste, but this has an almost stock photography feel to it. That's fine, and very popular and lucrative, but the subject here is too posed for someone like me, who would prefer something either grittier, less posed, more candid, or thoughtful. As well, there are minor imperfections that detract: overall the image may be too soft, and could benefit from sharpness in the eyes, there are highlights on her nose that could be softened, and the whites of her eyes could be smoothed or distracting elements cloned out. Her eyes could be well highlighted by a reflector or light source, adding even more interest. But this is being particular, because overall this is a great shot by an obvious talent.