Yes Alien and Blade Runner are classics. Gladiator and Thelma & Louise are debatable as well. American Gangster was aight but as yourself when was the last time you watched it? Forgettable film overall
But take a look at his cv:
Films[edit]
1977 The Duellists
1979 Alien
1982 Blade Runner
1985 Legend
1987 Someone to Watch Over Me
1989 Black Rain
1991 Thelma & Louise 6
1992 1492: Conquest of Paradise
1996 White Squall
1997 G.I. Jane
2000 Gladiator
2001 Hannibal
Black Hawk Down
2003 Matchstick Men
2005 Kingdom of Heaven
2006 A Good Year
2007 American Gangster
2008 Body of Lies
2010 Robin Hood
2012 Prometheus
2013 The Counselor
2014 Exodus: Gods and Kings
Exodus is currently sitting on about 28% on RT. Prometheus was one of the biggest clusterfukks in the last decade. Robin Hood, A Good Year and Hannibal were pathetic. And then we got the utter diarrhea he was shytting out in the 90s. GI Jane, White Squall and 1492
Now calling him one of the worst directors is more exaggerating for affect but the point still stands that he's released A LOT of trash. He has more bad films than good ones by a long distance.