Hey dude,

very very nice work, I must say. Like most of your other images this is technically superb, at least in my opinion. The varied color scheme clearly is my favorite part of this image, as it catches the viewer's attention at once. The nebula looks like rising fire which is awesome, though it is a bit chaotic and therefore lacks depth, but this is a very minor point.
Composition wise I think it's really interesting. Both, the row of planets as well as the nicely colored nebula lead the viewers' attention towards the center of the image where the sun is. The beautiful lighting on the main giant and it's great texture create an awesome atmosphere.
The only thing I'm not 100% sure about is the landscape at the bottom. I don't think it matches entirely and it's somewhat distracting, too. I guess it would have been a lot more atmospheric without the render, but that's just my personal opinion.

Now the down sides.
As many other pics in the space art gallery this doesn't have any particular meaning or message. It's just a very beautiful image for the eye, but not for our heads.
I know it's hard to come up with something unique in this genre these days, so I can't really give you proper critique. I just feel it lacks this certain wow-factor which can only be achieved when concept coheres with execution.

Nontheless it's another amazing work in your gallery and I must say I love it.

Cheers,
kire

Hey, of course I can write a critique! Sorry it took me a while, had a busy few days.
Anyhow, the first impression is definitely a positive one. The piece radiates a quite vivid feeling, which certainly is due to the many colours and also the light. I particularly enjoy the big planet and the area around it, especially the left. The way the blues of the space background contrast with the deep warm tones of the planet is just beautiful.
One thing that strikes me is the lack of an atmosphere, and I'm not sure if I like that. The planet needs no huge atmosphere, but I think a subtle indication of it would help ti fit it better into the piece, because right now its edge is rather sharp.

Also you might want to try and let the light which comes out from behind the underside of the planet bleed into the planet's edge a little. Just like if you watch a rather low sun from behind a sharp corner of a building, you will likely get a flary effect in your eye, causing the impression of the light being partly over the edge.

On to the nebulae. Overall it is not bad I think, but what I miss is a major structure or form, if that makes sense. It does appear a little like various textures and cloudy images blended together, which all have a seperate flow. And don't forget, the nebulae is a major compositional element in your piece. Done well, it will help to guide the eye up to your selling point, the planet.
What you could do is to try and sketch out the overall flow of the nebulae first, before you go into doing a polished version of it. And also keep in mind that some denser clouds might partly obscure the stars, which will give you a bit more variety. I think your stars look good, but they're visible pretty much everywhere in the space. Don't be afraid to hide them in places.
Mostly I think the nebulae needs work in the bottom two thirds. The top part where it approaches the small planets looks really sweet in my mind and doesn't need much of a change. Especially the colour interaction there is nice.

And last but not least, working our way down to the land...I'm generally note a huge fan of terragen, but I think your terrain in itself looks quite good and does its job in framing the image. It does certainly feel rather dead though in comparison to the rest of the image. Probably because it has mostly this brownish tone. I would certainly keep it subtle though, it's not the focus of your piece. But maybe add some detail in the shadows. I know that a celestial body without atmosphere would get a rather harsh lighting, but considering there are pretty much three light sources for the main planet, I think you can take some artistic license and give the shadows just some subtle detail, to add some interest. Plus that allows you to reflect a few more colours into the landmass.
Considering the height of your image it would maybe be nice to have something shooting up on the right side, towards the planet. Be it a comet or space craft or something. Needs not be discernible, just some subtle thing in the far background to help kick the eye back up to the planet. Or maybe a reworked nebulae will solve that, too. Or maybe a distant bunch of asteroids floating around, just something to get your eye moving again.

But yeah, overall I think this is quite well done. Am glad you went for some bold colours, rather than just an overall hue or tint. And the level of detail in both your main planet and the star field is very nice.
Well done!

Daniel