This one is such a classic that it has been made into a movie three times now -- 1951, 1982 and 2011. The second, John Carpenter's version, is the most faithful and the best of the three. John Campbell is writing this using his Stuart pen name.
The doppelganger theme is well carried out in this story and doppelgangers are instinctively creepy. Beyond that, what makes this story outstanding in my mind is that the characters are intensly heads-up and cooperative. This is one of those rare stories where no one in the story acts like an idiot or betrayer just to move the story along in a conventional way.
Campbell starts this out well. He sets up a wonderfully credible isolated community -- an Antarctic science research station. Up until satellite and radio technology advances of the 1990's this was a completely isolated environment during Antarctic winter. It's a wonderful way to set up a big problem but still have a small scale environment to tell the story in.
(Campbell wrote this in 1938, and, in fact, it would be hard to come up with something so unintentionally isolated in a modern, 2010's, setting. These days we have cell phones and communications satellites so even hiding behind the sun wouldn't work anymore. Speilberg tries in his SF movies such as Jurassic Park, but his efforts always look contrived.)
Nice entry into the story a science expedition goes to study something scientific and encounters some surprises. They now have to deal with the surprises. In this case, being far from any support or chain of command, they have to deal with it based on locally-available resources... themselves.
He comes up with a good science sounding explanation for why this space ship got frozen where it was 20 million years ago. (And his science is not too far off from modern science with has the Antarctic ice cap beginning about 15 million years ago.) He uses his science to describe why this location is the worst of the worst, weather-wise.
And he has the ship's propulsion getting tangled up with Earth's magnetic field which is why it comes in at the pole. It's not quite as neat as the weather because Earth's magnetic field is hardly exceptional compared with other bodies in the solar system -- if you're going to get tangled magnetically, it will be with Jupiter's. (But Jupiter's massive field was discovered in the 1960's, so I can forgive.)
Interesting... he has this ship and being that wandered away from it remain stationary -- frozen in place -- for 20 million years. That's stretching things a lot. Ice may be solid, but it moves around a lot compared to silicate-based rock. Even salt migrates big distances over geologic times. That's why salt usually ends up in salt domes. But in our story the ship and being stay just a few dozen to hundred feet below the surface for all that time? He's trying, but he's a bit off on this.
Good, he describes a mistake well. The ship is made of magnesium and starts to burn when they try to melt ice out of its partly-opened door with thermite -- a somewhat odd choice for melting ice, but ah well, I wasn't there. <grin> And all in all, a neat explanation of the ship frying itself into oblivion.
I love the argument between Blair and Copper over whether to thaw this thing out and examine it. The science and logic behind the arguments on both sides is still valid today. The only difference now, eighty years later, is availability of more sophisticated examining tools, and better contact with surrounding civilization -- nowadays it's hard to find a situation so isolated that an earthshaking event, and choice, such as this could not be kicked upstairs.
An aside: This brings up a fascinating issue that has plagued mankind's decision making ever since the telegraph became widespread: Who should make the choice -- the guy on the scene or the authority back at the home office? The most vivid contemporary example of this choice is the photo of Obama and staff watching the Osama Bin Laden raid in real time from the White House. Historians have noted that this issue first noticeably raised its head during the Crimean War in the 1850's when micromanagers back in London were telegraphing "good advice" to field commanders in the Black Sea area thousands of miles away, and expecting prompt and detailed reports of the situation so they could offer even more good advice. Campbell solved the issue in this story by locating it in the Antarctic which, until satellite communications was well developed in the 1980's, was completely cut off from the rest of the world during winter time. Spielberg in his movies about contemporary times adventures routinely works some some kind of accident to cut off the characters from outside information and interference in their choice making.
It's a blind spot in my writing that I don't like spending much effort on describing how people look. Campbell spends paragraphs describing how people look and their mannerisms, using lots of metaphors, such as McCready looking like a man of bronze. As a reader I have always skipped through that kind of stuff. But... I guess a lot of people think it's important and interesting. Personally, I'm much more interested in how people are thinking, which is why I often write as if I'm in the head of the main character.
Ah... an inconsistency. One of the first I've spotted. Blair is thawing the whole thing at one time. He isn't hacking off a small part, say a toe, and thawing that for the first round of study. If this creature is as dead as he believes, working on a small piece at a time for micro sliding would actually be easier than manhandling around the whole, now potentially rotting, thawed body. And it would lessen the chance of an irreversible mistake, which is one of Blair's arguments for doing the examination immediately rather than waiting for the whole body to be shipped off to a better equipped site.
He mentions that getting it back to New York City is going to be a long process. Interesting that Campbell, and his scientists, don't consider somewhere closer suitable. But not too surprising since as he is writing this LA, for instance, is hardly more than a small town -- oil and aircraft manufacturing haven't begun their boom there yet.
A third inconsistency now pops into mind. This thing looks horrible. It's hard to imagine something physical and long dead bringing up as much emotion as Campbell is describing. Further related inconsistency: After it begins its escape we discover this thing has been aware enough to be reading minds and doing some modest manipulating of them. If that's so, why is it letting all this fear flood out? It should be eminating awe and wonder at its strangeness, not fear, hate and ugly.