Honestly? I think the Thieves' World series needed a reboot at some point. The writers didn't really collaborate to establish ground rules for their world so a lot of it didn't mesh well. This is particularly notable with regards to magic; each writer addressed it with their own personal set of rules.
Worse still, somewhere around the fourth or fifth novel, the character Tempus became the series' Fonzie or Urkel (i.e. the unexpected breakout character), and the writers seemed collectively content to let him chew on the scenery to the point where it seemed that everyone else was a second banana. It was a really lousy development because the ensemble cast who preceded Tempus were mostly down-to-earth folks who overcame challenges through wits and skill, whereas Tempus was an invincible demigod, so the entire tone of the series changed (for the worse IMO).
Great concept. Lacking execution.
