The Robocop trilogy is a mixed bag. The first movie is a true sci-fi classic but the two sequels are both very poor. Unfortunately the poor quality of the sequels spoil the trilogy the first movie deserved.
Robocop (1987) directed by Paul Verhoeven (Total Recall) is a classic movie. Its brutal and exciting with a great performance by Peter Weller. Verhoeven superbly mixes the violent action with pretty intelligent sci-fi.
The sequel Robocop 2 (1990) was directed by Irvin Kershner (Empire Strikes Back) and written by Frank Miller (Sin City) so it should have been a good movie. Unfortunately its just a mess. The action looks cheap and the story is pretty silly. Peter Weller phones in his performance.
Robocop 3 (1993) was directed by Fred Dekker (The Monster Squad) and saw Robert John Burke replace Weller in the lead role. Amazingly it had the biggest budget of the trilogy but it looks very cheap and nasty. Sadly by this time the whole Robocop franchise looked very tired and the least said about the short lived TV series the better.
Verhoeven's Robocop is a true sci-fi masterpiece its just a shame the sequels failed to deliver.