Con - The arcade-y story and cutscenes. While I wasn't expecting a compelling story on the level of Solar Eclipse, I did expect something more than "Aliens are attacking. Go blow this stuff up. ...Good job. No go blow this other stuff up." The absence of live action footage is a disappointment as well, and while this does look amazing for its day, the CG pilots look rather soulless.
Pro - The visuals. This game may not look as good as Solar Eclipse, but it comes impressively close, which means the whole thing is a feast for the eyes. I practically drooled when I saw the first boss; man, I want to fly one of those things.
Con - The controls. As jerky as all get-out, making it an unnecessary pain to target all but the largest enemies. More importantly, you have all those tunnels to deal with, and even the surface has many narrow passages. A rail shooter which requires you to hug walls as much as this really ought to have better control.
Pro - The system of refilling your draining shields by blowing up enemies. This is an unusual concept, and it encourages you to play offensively instead of just bobbing and weaving around whatever comes your way. It also provides a reasonable excuse for blowing up stationary non-hostile targets, which would otherwise be good for nothing but racking up a few extra points. However...
Con - This system dominates the gameplay. Your shields drain too quickly, and combined with the huge boost you get from blowing up just one enemy, this makes getting shot a trivial event. Before long I had learned to ignore enemy fire and just attack anything that can give me a shield boost head-on.
Pro - The enemy designs. Just like in Solar Eclipse, the enemies all look very cool, and each one has a unique pattern of attack. It definitely keeps things from being monotonous.
Con - The music. It just seems like it belongs in a beat-em-up or 1st person shooter, not an on-rails space shooter. It's frustrating that the game has no option to change the volume balance, since the out-of-place blaring guitars almost drown out the sound effects.
Pro - The difficulty level. While I do have a complaint or two here (detailed above), overall Crystal Dynamics have once again proved that they know how to make a game highly challenging yet fair.