For the independent games development community, it's been a massive boost to sales. Having such a large marketplace allows developers of a niche games to find their audience, and being on Steam can have a large impact on the relative financial success of a project.
So many developers want to get their games on Steam that it presented Valve with a problem. How do they decide which games should get on their store? The old system was geared towards the major and minor publishers, with whom they no doubt have built quite a good rapport. However, in this new era of self-publishing, indie developers have to petition Valve directly to try and get onto their marketplace.
A new solution was required to curate the marketplace. One option would be allow almost everything, with only a few checks to make sure content was not inappropriate, illegal or otherwise undesirable. The other end of the spectrum would be to investigate everything about a game before allowing it on the service. Valve decided to pick a third option, and develop a community-based pathway to the market.
On the face of it this pathway is rather simple. Greenlight is integrated into the Steam user interface, and allows developers to post information about their game. The user base then votes on the content, and when a threshold is reached the game is released on the Steam store. In practice, there are hundreds of games available to vote for on Greenlight, and as of the time of writing only 35 have made it onto the store, with a further 62 "approved" but waiting.
It is difficult to appreciate exactly how this makes things easier for Valve. Greenlight does nothing to reduce the workload for them, in fact it seems to be increasing it. Rather than having a small team of people who are employed to talk to indie developers and get their games available for sale, they have a convoluted system that still requires this team of people but also requires people to moderate and maintain the Greenlight system.
To add another layer of frustration it is not an egalitarian solution. Niche, casual or first-time developers will find it much harder to achieve enough votes on Greenlight, especially those without established fan-bases or poor social marketing skills. Those games with publishers, which is no indication of quality, are able to bypass the system altogether. But getting yourself a publisher is not an easy task, and if you are already featured on Greenlight the influence of the publisher may not count for anything, as seen with the recent case of Paranautical Activity:
"...our message to indies regarding publishers is do it for your own reasons, but do not split your royalties with a publisher expecting an automatic 'Yes' on Greenlight."- Valve's Doug Lombardi in response to the Gamasutra article
The goal for many of these developers will be to get their product seen by as many people as possible, and while they might not make it through Greenlight, there are other options such as Desura, Gamersgate and GOG. Of course these all have their own requirements for acceptance, and what is acceptable for one may not be for another.
The solution for all developers is difficult but necessary. You either require a good publisher, or spend the time and effort to get your game noticed and sold at as many outlets as possible. For the customer, we need to be more discerning with our purchases and shop around a bit more. Supporting a variety of online stores will help build a more healthy and competitive marketplace which should help keep prices low and promote good customer service.
And Steam? Well, they don't really need my advice, but I'd certainly consider ditching Greenlight and coming up with a more viable solution. A small team that could assist independent developers as they move from game creation to game marketing and sales could make Steam a more welcoming and familiar place. It would require a lot of work, but I'd suggest it shouldn't be any more difficult than Greenlight.
I do think that Steam look like doubling-down on their community features though, with the arrival of Steam achievements, badges and levels. Gamification of the Steam service is being pushed through with beta feautres at the moment, and I wouldn't be surprised if this gets integrated with Greenlight. Valve is always looking for ways for people to engage with the Steam platform and make it their primary means of interacting with their game library, as well as certain social and news features.
I don't expect Greenlight to go anywhere, but I certainly hope for some improvements. At the moment it still feels like an awkward solution, and it doesn't appear to be working very well for a lot of developers (although perhaps better than the old method).