Thoroughly underrated. Let's not deny it: "Tito" is less dramatically meaty than Mozart's masterpieces, and in any case, his dramas have nothing on the simply sublime nature of his comedies.
However, "La Clemenza di Tito" has a lot to support it. The music is utterly divine: Sesto and Tito get gorgeous arias throughout, and the music for Annio is utterly exquisite. The love duet between Annio and Sevilia is perhaps my favourite Mozart piece, and that's without even discussing the magnificent character of Vitellia.

"Tito" will never be an audience favourite, given that its predictable plot hinges on a leader's clemency, rather than anything more invigorating. But I cherish it for its tightly-focussed character parts (the chorus appear only twice, and our six leads handle all the rest), its noble music, never showy but consistently haunting (that closing quintet of Act One, punctuated by an offstage chorus and the light of the Capitol burning down), and a sense that - as with so much of the great composer's music - this score so readily opens up the brilliant yet troubled nature of Mozart's mind, questioning his own talent and career, and only months from death.

Well worth it. See a good production (like the long-running Met production, most recently displayed in cinemas in 2012), and you'll understand. ( )