Go to the Steam Search page (you can do this by just going to search for a game, but leaving the search criteria blank). This will pull up a list of all of the games.
Just above the list table, on the right edge, is a "Sort By" dropdown that has a User Reviews option. That sorts all games by their review score.
On a related note, it pleases me deeply to see that One Finger Death Punch is on the front page of results, just below Hades and Half Life: Alyx. $5 game, two buttons, and one of the best games I've ever played.