One of my favourites. I think I've seen it dozens and dozens of times, but never in an actual movie theatre, since I was too young during it's initial release.
I was really struck by how well it still holds up, in terms of special effects, characters, story etc.
The theatre was packed as well. Sometimes you just can't beat that shared experience. They took a quick survey of the crowd just before the show and even though most of them had seen Aliens before, only ten percent of the people in the audience had seen it in the theatre during it's initial release.
They were showing off the digital projection, and it looked fantastic.
It's funny how I look forward to watching old favourites on the big screen more than the latest ones these days.