I have managed to find one gem out of the heap. That was Beat Hazard.
But in order to do so, I had to make a new Gamer Profile based in the US, because the Indie Marketplace is not accessible in Australia. This was rather annoying and was only so I could download the free XBLA games (Harm's Way...) only available in the US.
As such, I've not had major experience with the Indie Marketplace, aside from wondering why it's so difficult to access. From blind luck, the one game I did purchase turned out to be very good.
Another annoyance, it seems that I need to be connected to Live in order to play indie games, why is this so (security)?
So, I sure hope the indie marketplace is improved alot for 720. I feel it could certainly be a great feature if done right, to help bring devs up through the ranks (indie -> XBLA) and would stand out as a feature that I don't think the ps4 will have. QA is a more complicated issue that I'm not too sure how to handle (Community ratings - someone has to have bought the game to know what it's like/MS testers - could drive up the price of developing on the platform, but could be subsidised by players' XBL memberships).
I've taken "there's a security issue" to be the default reason for things that aren't as expected. Even if there is no obvious security issue.
I looked it up, and it turns out that Indie Games are not available in Australia because of some quirk with our classification system, such that all games need to be classified, or they are regarded as being refused classification. Though bizarrely, this only affects console content and not mobile content (hence, itunes is somehow exempt). :/ [url=http://www.kotaku.com.au/2011/10/we-might-get-xbox-live-indie-games-after-the-classification-review/]kotaku[/url]