First of all, some of my criticism might be negated if you read the book in english with the mindset of someone in the 1950s - or a profound knowledge of the technological advances regarding space up to this point.
I don't think this is a good book. I don't really think it's a bad book either, but it's leaning towards that and here is why. (Minor spoilers ahead)
1. The Writing: As I said before, I read a translation, so parts of this point might be mood. There are some internal inconsistencies, e.g. at some point in the book the main alien protagonist finds some astral coordinates which tell him where his homeplanet lies and the distance to it; the very first sentence of the very next paragraph tells the reader, he doesn't know how far away it is - excuse me, WHAT?
Then there's the usage of phrases like "He did X what would be a Y" for the aliens and the very confusing fact, that they use the same words for time periods, distances, etc. while the time periods at the very least differ greatly from earth's ones. I get it's supposed to make it all understandable, but couldn't you have worked with some kind of a glossary?
There is also the fact, that we never get an actual description of the aliens, not even when one of the earthlings sees on of their faces for the first time. Instead we have to piece it all together from small snippets: apparently they have tentacles instead of arms, lipless speech-organs seperated from their breathing system, they don't sit but rather hang from the ceiling(?) and can move their eyes individually from the other(s?). Somehow I had the impression they had more than two eyes, but it's never been told, as far as I can tell.
The dialogues are a bit strange too - mostly on the alien-side bit that might be intendend - as they tend to be very very in-depth and factual lines, even when they had an heated argument beforehand (again, possibly translation related).
2. The Characters: Let's start with the humans. The Rogers are a very... peculiar kind of people; the mother appears from time to time, but is basically an outline of a character. I can't even remember if she actually says anything. John Wing, the father, as far as I remember only once mentioned with his first name, is some kind of proto-Vulcan from Star Trek: he always is portrayed as a very thoughtful man and the only emotion the reader is told about is, how proud of his children he is (though mainly his two older sons). Yeah, the children... I'm fine with the two youngest ones, though they have as much impact as the mother, at least they act their age... as far as I can tell.
Donald, the oldest, is also rather alright, if you see him as a nerd. The feeling I had about him is he's more or less a more realistic version of his father, but in retrospect I can't really tell if he had any impact on the story, just like most of the rest of his family.
Edith was okay for the most part, I guess. The ten-year-old wanted to prove herself and her brothers and father, that she could do everything as well as they did, which is fine, all in all she seemed to be kind of tomboy-ish. The few times she actually left an impression, it seemed age-appropiate.
In total contrast to her brother Roger. Supposed to be twelve or thirteen he just acts... totally strange. I guess this is one serious case of "Like father, like son", but he seemed even more contrived than Mr. Wing. His total acceptance of the whole "if the girls think, they can do that, then you should show them and we'll see"-thing his father came up with, without him (Roger) showing any sign of reluctance is... mindboggling. I know they are supposed to be raised in this spirit of prove-it-mentality, but still... also when he was younger, he supposedly said to the kids of his elementary school (or something like that), that his dad found that mine in the mountains and THEY started to demand prove, until he stopped talking about it and they... I guess, forgot about the whole thing?
In contrast, the aliens are a bit more relatable. Sure, they are alien and have strange concepts and all, but as characters, I can't really any blame with them; they're just strange enough not to fall into the Alien-is-Human-trap but, up to a degree, also understandable. I don't quite see how Drai with his immense holes of knowledge came to be (and more to the point, stayed) the captain of the ship and the whole operation, but there might be some story to be told there.
3. The logical aspects: this here bothers me the most, to be honest. I feel there are so many logical gaps in this story, you could actually fly that spaceship of the aliens through those without scratching the paintjob. For example they've been in our solar-system for 20-30 of our years and didn't even notice any planets beyond Saturn or moons other than ours? They are supposed to be a highly advanced species, do they not? They cover several hundred parsecs in less than twenty-two days and can't even recognize a fluid on a planet? It's even moving, for god's sake! Plus, they're calling Earth "Iceworld", without having any idea of Ice, as far as I can tell. Also they're constantly worried about the planets temperature and never once about the temperature of outer space.
There is one mentioning in passing of another species they encountered, so they should know even more than they do present in this book.
I don't know whether any of this was general knowledge (well, other than thins like the planets and stuff) back when it was written, but from today's point of view it's just... wrong.
I like the general plot idea of tobacco being a very potent drug for other species and the aliens coming from a planet where sulfur isn't found as a solid or liquid, but only gaseous.
I do want to like Iceworld, I really do, but it needs so much polishing to do. It has so much potential. It could be a really great book I would recommend to everyone I know, but the way it is... I wouldn't buy it for any price. And that is just sad.