The twitchy gun play is off putting at first in NS2, but you soon get used to it. This game is very team based, and it's the best feeling when your team finally just clicks. Sadly though, a bad team can ruin the game play experience completely. One player is given the role as 'commander', this play will play the game in an RTS view, giving out orders, building structures etc, the rest of the team will play in FPS mode.
There is plenty of different weapons for the Marines, where as the Aliens transform into different creatures, ranging from a scuttling little dog like alien, to a giant rhino beast.
The levels are perfect arena, the lighting and ambient effects make it feel even more realistic. The top notch graphics and a really good engine, Spark.
Load times are absolutely terrible. Logging into a server took me five minutes each time. This is reported across the board. Apart from this, I had no technical problems. Zero lag in game, which is must given the twitchy gun-play mechanics.
I really enjoyed this game, but one that has to be played on mic and with a team of people you know.