Carrier Command: Gaea Mission is supposedly a remake of an old game which was revolutionary for its time. It's a weird way to make a game, really, copying a game which was revolutionary precisely because it didn't copy anything else. I guess the idea is that the concept the discovered by the original game was so good that it deserves a revisit.
I didn't play the original Carrier Command, so I'll look at this one on its own merits.
Carrier Command is a bit of a branched game. The biggest distinction is FPS parts vs. non-FPS parts: Occasionally, for plot reasons you are forced to play a very bad FPS section which has almost nothing to do with the rest of the game. Outside of these, the game is about conquering islands with a mothership (the carrier). There is a resource management/grand strategy game on that level - it's not really a full game; it's very basic. I'll call it a grand strategy "gamelet". Then when attacking an island, it becomes a tactical RTS, uh, gamelet. There is your carrier, and two whole (albeit configurable) unit types. Then, you can actually take control of the units and drive them, so then it becomes a tank driving or helicopter flying gamelet.
So as you can see, Carrier Command is really not one game, but several different games (grand strategy, tactical RTS, FPS, vehicle sim) rolled into one. Neither of them is really any good, for the vehicle sim part the visuals are kind of pretty, but no part of the game really has any depth, and I'm afraid 5 shallow games just isn't as good as one deep game. I'd rather play a good FPS, or a good RTS, or a good helicopter attack sim than Carrier Command, at least after Carrier Command's initial 1-2 hours of novelty are over.
Also troublesome is how these different gamelets are composed. The way that the FPS and grand strategy bits are handled, it feels like "Here, play this game for an hour. Done? Now then, for something completely different..." It just throws you back and forth. I could have just went and gotten 2 decent games, and then switched between them myself - and they'd both be good games. There's one (sorta) exception: The transition between the tactical RTS and vehicle sim is not so bad. It reminds me of being the commander in Battlefield 2: You get the same map, a very sluggish but well-armed carrier, and you issue basic move and attack commands when you switch to the map, or you can take control of a vehicle yourself.
This RTS/vehicle sim blend is the main part of the game. 90% of your time is spent in it, it's the only part that doesn't look like crap, and it's the only part that needs meaningful input from you as the player. Taken on its own, it's fun for an hour or two, but quickly becomes tedious because they didn't bother fleshing it out: There's two unit types, a Walrus (basically a BTR) and a Manta (a VTOL aircraft). You can have up to 4 of either, although the AI is so terrible that only solo ever makes sense. The enemy can have much larger numbers and can also have robots (irrelevant cannon fodder infantry with shit health and shit damage), AA guns and AT guns. You get a grand total of 5 enemy types to fight through many, many hours, and 2 of them are the same as your units, 1 is useless, and the remaining 2 are stationary turrets. If only there was more variety in this stage, it could just be entertaining enough to save the rest of the game, but as it is, it's a drudge.
The AI sucks, too. Enemies have absolutely no cohesion, it's like they are just some random dudes hanging around. It just doesn't feel at all like attacking a single force occupying multiple bases across the island. You can drag away and pick off the garrison units one by one and nobody except the units you directly engage will ever care. Bases will never reinforce each other. Even enemies on one side of a large base will not help the defenders on the other. Besides this, pathfinding is also godawful. This is one of the biggest flaws that prevent you from enjoying the game: It is just such an enormous pain to make units go from point A to point B. They get confused by trees, they take huge detours to avoid going up a gentle hill, they get stuck in deadlocks with each other on narrow roads (one reason why you tend to go solo, the extra units just get in each other's way). It seems that pathfinding divides the map into a very large grid and then works from there, so sometimes the bridges will end up right between two grid points and the units think there's no bridge and refuse to cross it. Which is *slow*. I guess they went for a realistic physics model for the controls, but all it does is drag out the gameplay. I don't see why the vehicles couldn't just handle like, I dunno, Battlefield 2. They handle like bricks. So your one recourse is to let the AI deal with driving them, because it's such a pain, but the AI is imbecilic and will lose engagements you could easily have won yourself. Seriously, the cunning tactic of "sit in place and fire at the enemy until your guns overheat" manages to outperform the AI by 5-10 times.
On a higher level, the islands themselves are not designed very well. If you don't get any story events forcing an FPS section for that island, then the basic mission structure is always the same: First beat 3 secondary objectives, then go to the command center and hack it (by standing next to it for 10 seconds). The secondary objectives can be "hack the firewalls" (which means go to each non-main base and stand in it for 3 seconds) or "disrupt the shield" (which means go to each non-main base and destroy a special building) or "eliminate scramblers" (which is the same as the shield but instead of blocking the command center with a shield, the scramblers make your units able to go only a short distance from your carrier until destroyed). These are all the same basic mission. Together with the way island topology is designed (lots of impassable cliffs blocking all creative paths) and the braindead AI, the net result is that every single island assault is "attack 3 secondary bases, then attack main base". Until you get the Gatling Gun and Mark 2 Armor (you pretty much get these for both aircraft and land unit around the same time) the game is ridiculously hard, after it is effortlessly easy. It is never really fun, and because the AI is dumb and the units are sluggish and the paradoxically the islands are so *linear* you cannot breeze through either.
So, the main game is a nice idea but flawed. That leaves us the grand strategy and the FPS parts. The former is just pointless, and again, drags out gameplay needlessly. There's an enemy carrier which attacks your islands while you're elsewhere, and there's no way to defend, either you have to come over to the attacked island (which makes the enemy carrier run away) or you just let it be and recapture them (UGH). Either way, pointless artificial padding. I would actually be happier if there was no map and just a branching mission selection menu. You can have production islands (make weapons and replacement units), resource islands (not sure what they do) and defense islands (supposedly harder to capture). But only the number of production islands matters, and fairly early you can get as many as you'd ever need. So after a while, it ceases to matter which islands you hold or lose.
Lastly, there's the FPS parts. Jesus, how fucking terrible. The mouse sensitivity is shit. The graphics just don't work for an FPS. The controls are basic (no jumping!). You only have 1 gun (one time I got to use a laser for like, 1 minute). There are only 3 enemies and they are all the same infantry with a rifle. The missions are not challenging. Very quickly I found myself rushing through the FPS parts because of how terrible they are, and the only consolation is that usually the FPS mission saves you the bother of capturing the island.
By the way, I just feel like mentioning the story. There's a story. It is cliche, it is racist, it is xenophobic (hurr evil chinamen with chinaman accents do evil things because they are assholes like all chinese, while noble westerners nobly fight them because they have noble hearts USA is always good guys). It is also painfully, horribly, indescribably bad. The accents, the plot, the dialogue, it's all fingernails on a blackboard. I'll endure all sorts of shitty storytelling just out of curiosity about what happens next - even I couldn't do it, after the third one or so I just started skipping the cutscenes when I could. The main character has one of the worst fake British accents (although it sounds more like Australian, I guess) I have heard, and I have heard quite a few.
Enjoying Carrier Command is a matter of being bored enough. You are never bored quite enough to really consider it fun, but if you are just that bored then it works as a diversion. For a while. Not long enough to endure through the whole game. Paradoxical as it may sound, this game has to last a fifth of the time, and have a fifth of the "stuff" (and possibly have five times the variety) to really be worth playing.