My girlfriend and I saw a Sunday matinee of the new Thing, and we both agreed it was the best prequel either one of us have ever seen. It had both of us on the edge of our seats for pretty much the entire movie, managed to maintain a scary atmosphere, but more to the point, it never felt forced or tacked on.
Here's the thing, if you'll pardon the expression - the stuff at the Norwegian base in the first movie was very, very odd. The prequel not only had to account for it, but somehow make it into a coherent story. And it succeeded. It not only set up the John Carpenter movie perfectly, it actually did feel like it was fleshing out the backstory, rather than tacking something on.
(For comparison, take the Star Wars prequels, which feel like they are taking place in an entirely different galaxy than the first trilogy.)
As far as we were concerned (and we watched the blu-ray of the John Carpenter Thing about two weeks before seeing the prequel), the first movie set a high bar, and the prequel matched it. Far from boring, it was actually a very scary movie, and neither one of us ended up checking our watches once during the entire movie.
So, this is one case where I pretty much have to disagree with Bob entirely.