Not bad. The texture's pretty good, as are the clouds. Really the only thing I can find to critique is the lighting. My points are kind of minor, but I feel isn't quite "complete" with them.
The clouds just seem kind of "slapped on", as opposed to actually being part of the planet due to not casting shadows, and it's pretty hard to tell where the light is coming from (which is compounded by the aforementioned lack of cloud shadows).
The darkness on the "unlit" side of the planet is indistinct, practically non-existent, and really makes the whole planet appear more as a flat disk than a sphere. I get that realistic hard shadows aren't universally considered appealing, but I can't help but think that, had the shadow, soft as it is, had been doubled, say, it would have helped sell the shape of the planet more, as well as making the molten areas of the planet "pop" more.
But other than those, it's really just a bog-standard planet beauty-shot. A well made one, though, to be sure.