I saw that you requested Critiques so I thought I'd see if I could help out.

First off, straight out, I don't like the text. I don't like the font choice nor the text placement, as well as the solid colour of it. I understand that your name is across the horse to try and prevent thieves, but still, you could choose a more subtle text for that like Verdana, and make it smaller, and lower the opacity a bit, and it would still have the same effect of deterring thieves. The text 'Hera' and the little patterns alongside it is nice, but not placed right over the horse like that. I think I would have preferred to see the text placed perhaps hovering just over the horse's neck, on the background, somewhere. Again, with opacity lowered a bit. The text 'Queen of the Gods' gets overlooked in that top corner, and when you do see it, it feels out of place.
Regarding text I myself always try to keep things simple - a simple text like Times New Roman for names, and Verdana or Trebuchet for other things - I don't often venture away from them. Remember, you want your text to give more substance to an image, not to take it away, and I feel that the way you've done the text here takes away from the image. I think some more bold, simple text would have a bigger impact on helping to portray that this is Hera.

Next thing I notice is the border. While it's nice and everything, I think this image might have been advantaged by a simple black border around it.

Now as I look at the horse I notice many many things. Especially the cutting, almost all the way around the horse, is very jagged and pixelated, and there are chunks of the horse's original background still visible, notably around its nose, chest, back and between its back legs. I really do love the eye however ^^ I like how you painted the forelock and tail, but along the topside of the neck/mane, it almost looks a bit too square? Not sure, but there's just something that doesn't look right about it.

With the horse's feet, they seem to be floating on the water. It could be that Hera is Queen of the Gods and can therefore walk on water, but even then, she would at least have a shadow and leave some kind of mark on the water? I would have loved to see her feet blended into the water as if she was standing in it, you could have painted in splashes (if you search on deviantART you might be able to find some splash brushes and such which are handy too!). And also, looking at the feet, I can see some grass from the original background against her hooves/legs, which could be cloned out fairly easily.

Now, overall, the whole image's lighting seems off. I look at the foreground (cracked desert) and the light seems to be coming from the right. But the mountains in the backgrounds, the light seems to be coming from the left, as the shadowy side of the mountain is on the right, yeah? And the horse is heavily shadowed, but nothing in the background is heavily shadowed, so it just feels, out of place. The sky in the background seems to suggest that the sun is breaking through the clouds, and if anything the horse does fit that sort of lighting, but the rest of the background elements does not. I understand that the background was a 'remade' but maybe you could have edited it a bit to try and get the lighting to 'fit' a bit more. Also, the horse seems a little bit too dark for the background, but I think if you raised the contrast and lowered the brightness slightly on the background, it would fit a bit more.

Lastly, the perspective of the horse relative to the background is a bit off. Having the horse placed this far in the foreground, it feels like one should be 'looking up' at it more. Perspectives are icky things to deal with, and are very hard to explain. I think even if the horse was moved 'up' or a bit further into the background, the perspective would be more fitting.

I hope I explained everything OK, and I hope my comments helped, if only a bit.