IMO it's not worth getting. If you want a good set get the quadrillogy and all your prayers will be answered.
I got the Legacy collection long before the quad set so I never bothered to trade it in. it DOES have some pretty cool features on ALIEN & ALIENS, but all ALIEN3 and A:R got was theatrical trailers :-/ and some A:R video game trailer (boring).
if you could find the Alien and Aliens movies seperately than I'd suggest that.
because they DO have features not shown in the Quad.