I suspect those who actually try to defend this film only feel compelled to do so because FC, Pacino and Puzo were involved in its making. If it was an identical film directed and written by someone else (but still without Duval and with Sofia Coppola), I have no doubt that literally almost everyone would have been listing it as one of the "worst sequels of all time", next to such antifavorites as "Highlander II" or "Batman and Robin"...
To each his own.
I like the movie because despite its flaws -- it's still good. The same can't be said for a movie like The Phantom Menace (the kid was worse than Sophia, BTW).
Perhaps this movie would satisfy the haters if it were scaled down by a half hour, hell, I might like it a lot better that way too.