There have been tons of complaints on them, but there are also LOTS of them on the road.
Find one cheap enough in good shape (they don't hold their value like other Diesels) and you can make them pretty bullet proof.
I read a lot of Diesel forums and they're really not supposed to be a bad motor once a few things are changed.
As far as the negative 7.3 comment, one paper they are down on power compared to a lot of the newer motors but hook a heavy load up to one and you really wouldn't know the difference.
I drive a Cummins 5.9 and an '01 Ford F-350 with a 7.3. With a full load on them there isn't much difference.
