Valve is promising to "closely monitor" game submissions and use human input to verify that Steam's store algorithm is surfacing the truly interesting titles. Combine that with greater transparency and you may not have to worry that a hastily produced knockoff is getting more attention than an original gem.
The gaming giant is also rethinking its Curators feature to give these advisors more power when recommending titles for you to play. It'll be easier to Curators to create personal lists that offer specific advice, such as games to buy during a sale. They'll also get to showcase more of their own content (such as their YouTube material), and it should be faster for them to obtain pre-release access to a title. Curators are optional, so you don't have to see their selections if you're comfortable shopping on your own.
There's still no firm date for when Steam Direct will go live. However, the fee by itself already gives a feel for what you can expect. While $100 isn't a throwaway amount, it's small enough that even a solo part-time developer can publish on Steam with relatively little trouble. If Valve had ventured toward the higher end of its fee range (it was leaning toward $500, but could have gone as high as $5,000), it might have limited Steam Direct to more dedicated creators. In other words, you can expect to see more personal projects that aren't quite so focused on turning a profit.