Greenlight still has a lot of problems
1. The downvote
It holds no purpose whatsoever. It may have done when putting something on there was free, but not anymore. If people don't want the game, they wouldn't look at it.
2. Prone to votebombs
Okay, take the Yogscast for example. If they suddenly said "HEY, GO VOTE FOR THIS stuff", everyone would instantly dive in and vote for it, and not touch anything else. I suppose this could be fixed by making rewards if you vote for a lot of different things, but that would promote mindless voting on everything. It's a tough one.
3. Feels like a popularity contest
Hell, isn't every vote-for-me thing one? It's a minor issue, but valve should add a search-by-genre feature, and results should not be based on date or popularity: It should be totally random each time.
4. Lack of quality standards
There should at least be some standards on there. Like requiring a playable demo, a gameplay video, and maybe some other things.
£0.02