Yes, the set is worth every penny....
Except that eventually, the long foldout packaging gets tiresome and frustrating in the end.
The fact they got 5 of the original 7 members of the cast from the first movie (Yaphet Kotto and Ian Holm were no shows)to do commentary was a coup!
In the extras for the first movie, there are often snippets and footages of scenes not used in the finished film, like the Alien's tail about to stab Brett in the back, Kane actually seen being taken on board the ship, actor Jon Finch as Kane before he was replaced (in a way I was glad he was replaced, Jon Finch was just too pretty boyish for something so horrible to happen to him), Veronica Cartwright slipping and falling on her butt after she was sprayed with blood in the chest bursting scene. There are more deleted scenes not seen in the original 20th anniversary DvD, and even material from ALIEN's Laserdisc release.
I have yet to look through the extras in the other three films, it will take a LONG WHILE to go through everything.

But so far so good!