I just went through all the features. David's illustrations goes into quite a lot of detail. Phobos is weird, but interesting short film, isn't there also something like this for Prometheus with crew interviews and such?. I really like Advent, that's my favourite.
The deleted scenes are all good, they should have been left in the film. I especially like The Crossing and Daniels Apartment on Earth. They add a bit more depth.
Watching it again on blu-ray, such a shame there might not be a sequel now, but instead Aliens remake/reboot (probably). The series is going in such an interesting direction to fall back to derivativeness.