From publisher blurb:
The thief class was added to the game very early on by a player who felt its absence was glaring. It was later picked up and published officially. While there has been much debate about the necessity for this class, it's pretty apparent that the class, as published in any old school edition, was not particularly effective at either thieving, combat, or really, anything but dying frequently.
The OSR Rogue is my attempt at a replacement class for the thief (the Tomb Robber was another, earlier effort), borrwing a great deal from later editions attempts at improvements, but compatible with older games.