Sorry about lateness, but university is taking its toll on my free time.
I'll try to avoid repeating karajorma's review, so I'll more highlight specific points rather than attempt a comprehensive review.
Storyline - 3.0As said, the mission story setup is very well done, aptly conveying the chaos and confusion of a blitzkrieg'd front line. Slight fudging is necessary to slot the mission into the existing FS2 plot, but it is ultimately a plausible, possible mission. Unfortunately, it's not perfect: the story does tail off towards the end, and a marvellous opportunity to tie the events of Bearbaiting/High Noon into the mission outcome (where saving the Arche and Neith gives the Colossus a resounding success against the Sathanas, and losing both ships results in the Colossus' destruction or near destruction) is missed. The debriefings ought to have consisted of more than a summary of your performance - if not an update of the wider situation, then at least some musings on the death and destructon witnessed during the battle. Additionally, the lack of a 'proper' briefing means that the player is unaware of what forces he has under his command and what ships he must protect. This can be forgiven, though, as the current briefing setup is just hella cool.
Balance - 4.0This mission is, to an extent, quite hard - while I can, with effort, save the Arche, defending the Neith from multiple fighters and bombers and an incoming destroyer is beyond my abilities. That said, the debriefing doesn't bawl you out for failing objectives, so it's not really a problem. One suggestion I would make is that the player is given a better gun - even a simple Prom-S attached to his Subach would improve matters greatly. I make this suggestion because I believe it would better serve the 'feel' of the mission, which I shall cover below; it is not really so much of a negative or mark against the mission. On the other hand, I did find myself being massively overwhelmed by Shivan fighters and bombers when the time came for me to jump out, meaning that I rarely made it back to base. It would be best if the player could have some breathing room in order to jump out, especially since the mission ends with Shivans controlling the entire battlefield and few to no allies remaining to help the player.
Design - 4.0As mentioned, there are a few minor flaws, like a missing RTB directive and 'ghost ship messaging,' and design decisions that should perhaps have gone the other way, relating to awareness of starting forces. Also, the theatre is fairly flat, and while I understand and sympathise with not wanting to have spaceships every-crazy-which-way even though it'd be like that in 'real life,' the remains of a battlefield should have had some more chaotically placed vessels thrown out of the main plane of battle, up as well as along. The Beleth, at least, could have been placed above or below the battlefield in order to provide some variation to the flatness. It is, though, not a critical issue.
Gameplay - 4.5Firstly, the mission does a good job of creating a large battle without screwing it up, if by having it before the mission starts. Secondly, and more importantly, I thoroughly enjoyed the 'puzzle' feel of the mission and found it quite different to most other missions that I've played. As the player takes command (of sorts) in the post-battle confusion, he is forced to analyse the battle and figure out what to do, and when to do it, in order to save the Arche and the Neith. If a player runs around chasing fighters, the Shivan capital ships destroy the Arche. If he sends everyone to destroy the Shivan beams, bombers destroy his corvette. If he focuses solely on the corvette, a fighter wing destroys a repair transport, preventing the Neith's escape. The player must retain situational awareness at all times, and must go beyond simply 'shooting Shivans;' he must engage his brain if he is to come through victorious.
(This is why I suggest the player is given slightly better fighter armanent - if the player doesn't have to spend so much time pounding on Astaroths and Taurvis with Subach HLs, he can spend more time organising the defence of the allied corvette and destroyer.)
Overall Rating - 4.0Oh, and I'm still not sure as to how I can save the GVD Neith.