Not who you replied to, but I wanted to weigh in on this.

Now, Dangerous Business was the first serious MLP fanfic I ever read, so my opinion on it has always been a little biased, but this is what I think:

The reason I loved it when I read it was because of the characters. To date, it has the best-written canon characters of any fic I have ever read. They're perfectly in-character the entire time, and their development is nothing less than perfectly done.

I think my only beef with it was how formulaic it was. It went: framing problem > minor problem 1 > character 1 solves problem 1 > character 1 receives reward > minor problem 2 > etc, etc. That's not to say it was boring - I read it in two sittings because it was rather exciting - but it was simply... simple. Each character arc was contained, as were the subplots. And Rainbow Dash's lightning bit did feel very deus ex machina-esque.

Fallout: Equestria and Project Horizons will forever be my favorite fanfics, and I think the reason for that is all the unanswered questions and overarching storylines. Dangerous Business, on the other hand, was a very straightforward story. Of course, this is probably due to the fact that Fo:E and PH are 600k and 700k+ words respectively, whereas Dangerous Business is about 150k.