I'm not usually crazy about Keanu Reeves' acting capabilities, or his roles. I did like him in the Matrix, I thought he fit rather well. I liked everything about that movie, especially the lead agent!!!!!
Jet Li kicked some serious ass in Lethal Weapon 4 (Still trying to figure out how he did that somersault kick that was in all the trailers), but he does not belong as a replacement character for Keanu Reeves.
If there's one thing I absolutely hate in sequel movies, it's when they don't get the same actor to play the same role as the first movie. It drives me up the wall. When I think of Neo, I think of Keanu Reeves, not Jet Li. Morpheus is Lawrence Fishburne, not (arrrrgh) Will Smith. Jet Li would be great in Matrix movies - maybe as an agent or something.