Everyone knows the rule of trilogies, the third one usually sucks. There are some exceptions- Nolan's Dark Knight movies, Bourne ( Now sadly tainted by that awful, unnecessary fourth entry.), but in general this rule always applies, and Robocop is a prime example of a trilogy gone wrong. Enough has been written about the original, it's an exemplary 80's sci fi movie that still impesses today. Thoughtful, melancholic, satirical and with a lot more to say than a film with THAT title should be able to deliver.
I also believe that Robocop 2 is a highly underrated sequel. To often lumped in with the third one as a failure, i think it's aged remarkably well. It retains the wit and violence of it's predecessor, and possesses a great cast, mostly returnees from the original. The finale is a spectacular display of destruction and heroics, that now seems oddly similar to the first Iron Man's (2008) climactic battle! I cannot defend the third, however. It really is rank. Special features are solely focused on Robocop 1, and are plentiful, it also has the gorier, nastier Director's Cut. Sadly 2 receives nothing more than trailers. Bah! Very good dvd transfers and sound quality on all three. Especially if you grew up watching these on vhs. Classic!