I've finally got to play Last Survivor to the end, and although it's very short, it's pretty amazing. I loved the look and atmosphere, and running back to the Narcissus was nerve-racking. I didn't like, though, the fact that there's no animation or cutscene after entering the shuttle, the game just abruptly stops. Also the narration from Ripley was missing in the PS3 version; I saw subtitles and the radar animation, but no voice or sound whatsoever.
All in all, CE and LS were astounding. I loved the original Alien feel and I hope we'll get more quality DLC similar to those two.