All of Roger Moore's are fucking awful. Even his "good" ones, The Spy Who Loved Me and For Your Eyes Only, are still pretty bad. I'd probably single out Moonraker or Octopussy as the worst of that bunch, but they're really all virtually unwatchable for me.
Every Bond has a couple stinkers on their resume (except Craig, whose three I all love unabashedly) but no one else put a complete streak of shit from beginning to end like Moore did. I don't really blame the guy, he didn't write or direct those things, but he was just terribly miscast for the part.