Just read John. W. Campbell's Who Goes There? - the short story/novella which inspired the film The Thing From Another World, and then later, John Carpenter's The Thing (fantastic film, by the way: if you haven't seen it: see it).

I thought the story was good, but not as good as it could have been. Campbell definitely gets across the sense of paranoia which forms the core of the premise. I felt it myself as I was reading it - wondering if a particular character was a monster or not, and never quite guessing right.

But the narrative is bogged down (particularly at the beginning) with far too much scientific information which, I know is a style thing, but it detracts from the flow of the story. You can't assume that all of your readers are into that kind of stuff - a small percentage of Sci-fi fans are, nowadays.

The dialogue was at times confusing, but I wanted to like the story, so I read and re-read. Overall, decent, especially the action scenes. But a let down nonetheless.