Many moons ago, early in my kit building days, I attempted one of these kits. The result was not good: The car was not square and had serious gaps in the corners. I ran it for a while (it didn't run too well either...) and finally scrapped it .
Since that time I have built many kits--Branchline, Proto, Intermountain, F&C, Eel River, Tichy, etc. I am confident that my kit-building skills have improved
I recently was at a train show and saw a few E&B kits on sale cheap. I picked one up to see what I could do with it.
My new attempt is square and gaps are minimal, but the fact of the matter is the car doesn't look as good as the Bowser and Kato shake-the Box kits do. And it takes a lot more work. I haven't tried Intermountain's version, which I am sure is more work (due to more parts, etc.) but I am willing to bet the result is better.
In any case, it was an interesting lesson learned. Even if the kits are really cheap, the results are not good enough in today's market.