I haven't posted in a while, but this contest interests me quite a bit. Not as a mapper, but as someone that can give decent feedback.
A few things I think...
1. The first post reads "YES you can edit the gameplay slightly, it just needs to be obviously this map, no making new routes." Correct me if I'm wrong, but to me that means that if there's a minor gameplay adjustment necessary in an area, like adding a few additional brushes, that it's not going to be a big deal. It sounds like you have to keep the overall layout, routes, and areas the same, but if you need to use brushes to make some LOS blocks or alter the displacements it won't be a problem.
2. To the people complaining about it... if you really don't like it, then don't compete. It's really not that complex. I'm sure Valve has playtested internally before releasing this, since it'd be pretty stupid otherwise. Can we just give them the benefit of the doubt? Complaining achieves nothing.
3. The people that "always win" deserve to win because their work is of such high quality. If you want your work to win then make sure it's of that quality as well. People like me are happy to give feedback, as long as you're willing to listen (not saying you have to do what we say, but rather that you take our advice seriously).
4. Every other contest has given participant badges, correct? There's nothing noting that this will be any different, but if people are competing just to get a badge then they're probably not going to win anyway.
5. I'm happy to provide feedback. I'll post in the threads that interest me the most, but if someone really wants feedback and isn't getting any then feel free to send me a PM.
6. Why so serious? I think the best maps are from people that come up with a fun idea and then have fun with it. I think it's clear that a unique idea will win, so if your map starts looking like Dustbowl or Gravel Pit you're probably best rethinking it.
/Mr Obvious signing off