I think I can speak for most here when I say we love it when folks play our missions and comment on them. Only problem is with some of the really popular missions out there and many players just doing the dailies it can be hard for a new mission or series to get any attention as they're buried at the bottom of the default search lists. That's something I'd like to change.
Now I don't have the time to do the detailed reviews that evil does, but I'd be more then happy to play and offer advice on your mission in exchange for a play through of mine (Ep 1 is out already, working on Ep 2 now). This is mainly for the guys trying to get their mission out of the review queue or otherwise have not had many plays of theirs.
Play Star Trek: Allegiance - my first series in the Foundry
It is true that new missions can get buried in the pile by more popular missions. Authors need to create postings here in the The Foundry For Star Trek Online - Mission Database to bring their missions to the attention of other players. They can also advertise them on Starbase UGC as well. On these forums you create the posting and then bump it every few days. I always try to bump mine on Friday morning each week when I am advertising my missions.
I try to highlight good missions as well as help authors improve their missions, but the author is the best sales person for their work.