Awesome and old school.
As an older gamer who grew up watching the Alien movies I was looking forward to this game. I still love 2D shooters and have enjoyed Wayforward games before (such as Contra DS) so I'm happy to report that this game was a lot of fun.
The game has the atmosphere of the series with all the sound effects in order and a feeling of claustrophobia. The blasting action is satisfying, though the controls take a little time before you are accustomed. For example, using the touchscreen to reload is fiddly.
The game has a fixed cast of marines all with their own personalities, comments and replies. Additional play-through attempts are required to see them all. The player starts with 4 marines. Losing a marine sees them actually dead, so functionally they are a lives system. Additional marines (extra lives) can be found throughout the game, though a new marine will only join if there is currently less the 4 marines in your squad. In many cases you will able to return later to recruit if necessary.
The game plays out similar to a Metroid game of old. Locations are shut off until the correct piece of equipment is found allowing progression. This comparison to a 'metroidvania' may sound like a substantial game, but it is actually quite short; I finished it in little over 5 hours. Still I recommend it for anybody into the style of game described and say it is a must have for Aliens fans. There is little else like it on the DS, the game is quite challenging and I know I will play it again (particularly on long flights!).