No, the conducting is not horrendous. You may not like Klemperer's approach, and it's a unique conception of the work to be sure, but one that is wholly convincing and incredibly effective in its way. It's certainly not as dynamic and theatrical as other recordings, but then again Fidelio isn't the most dramatically effective or seamlessly paced opera anyways. What it is is a supreme expression of the resilience of the human spirit, and as Peter Gutmann writes of Klemperer's recording, "its nobility and dignity fit the overarching themes, and its monolithic outlook provides a sense of continuity to unify what admittedly is a disjointed composition." Klemperer is able impart a sense of greatness, of spirituality that I find very impressive and that has made a great impact on many listeners. The superb singing and characterizations only increase it's power.