I've just watched the Director's Cut of Aliens (again) and it is astonishingly good. Not just good as in 'good for an 80s movie', but good as in 'would still be fantastic even if it was only just released this year.'
James Cameron's direction is exceptional. There's not a single wasted shot. Sure, some of the special effects are very dated, but the effects for the aliens are superb.
The aliens look and feel solid, real, palpable. Their presence is very strong, even though we rarely see a full body shot. Cameron knew that 'less is more', and was very selective about how much he showed.
The plot is strongly character-driven, and the characters themselves are believable, despite being painted with broad brushstrokes.
The more you look back to movies like Aliens, the more you realise how badly CGI has ruined films.