The good father's With Us Today: on the Real Presence of Jesus Christ in the Eucharist is one of the most heartfelt books I've read on the subject (and this is no small number, given that reading books on the Eucharist has been my only academic work this semester). As I said in my notes on the work, Fr. Hardon's love for our Eucharistic Lord is obvious. He's quite inspiring.
More information on the cause can be found here.