Dipping now into the Thief Anniversary Contest as requested - I want to start by saying that I myself am not a huge fan of contest missions on average because of the time limit imposed on fan mission authors. Some of them pull off amazing things given only two months or so to work with - but for the most part when playing contest missions I get the feeling that given much more time the mission could have been so much more than it ended up being.
That may be an unpopular opinion (and is only my own) but I do know that most of my favorite missions and campaigns have time frames listed in years in their development times.. so take that for what its worth. I do enjoy when an author goes back and fleshes out their missions more after the contest is over, however - as many that I've played in the past were begging to me continued after the time frame was over to give the whole experience that the author intended.
I myself am more of a fan of large, open and sprawling fan missions and I find most contests have very small spaces to work with and it makes me feel sort of claustrophobic as a player.. I don't know how to explain it really. Anyway, now that my personal disclaimer about contests is out of the way.. On with the show!