I heard most of it on the radio. Radvanovsky sounded rather strange - good high notes, good low notes, but otherwise a very fluttery sound. Alvarez was fine, Hvorostovsky quite good but not very Italianate (however, he was a great deal better than when I last saw him, as a phoned-in Rigoletto at Covent Garden). Dolora Zajick was the star of the show, IMO. (Does anyone know that, in reality, her surname is pronounced "ZIGHTS"?)
It's Verdi's most tuneful opera, IMO, and I think that the convoluted plot is no worse than many others (e.g. Rimsky-Korsakov's The Tsar's Bride at Covent Garden, which I saw last week: full of holes but nice music).
Italian opera at the Met: the audience is just desperate to applaud everything, whenever there's the slightest pause.
And in answer to Kay's question: the average age of opera-goers of some operas that I've seen recently was, relatively speaking, quite young. Examples: Peter Maxwell Davies's Kommilitonen! (to be seen at the Juilliard in November) and Mark-Anthony Turnage's Anna Nicole.