You can filter games by genre, platform or players on the start screen so that only games that you are interested in are displayed.
What you get in addition are user comments - which are not available for Steam store games - and options to to rate a game up or down, report a game, or add a game to the favorites. You get screenshots and sometimes videos, information about the genre, platform and languages, as well as a description that informs you on game mechanics. The individual game pages offer the same set of information that Steam store games offer. Unless you happen to play games on iOS or Android, as many games listed on Steam Greenlight at the moment appear to be ports from those mobile systems. Please note that this is more about independent games than full price titles and that the majority of gamers have probably never heard of the games that are listed on Steam Greenlight. Every Steam member has a vote, and games with many positive votes or promise will be added to the Steam store eventually.