I remember seeing this game for sale in places like Wal-Mart and Best Buy when it was new, never seen a copy sell before, and I learned that the game had STARFORCE which was debatably a very destructive DRM method at the time. I read reviews and learned the game had quite a few bugs. Well, a decade later, the DRM's removed and a handful of bugs are patched, the game's very playable. How is it? Well...
Graphics: They've aged pretty well for a game from that era, to be honest. Lot of stuff looks great, the aesthetic doesn't do much that's displeasing unless it's intentional, such as for cultists and mutants. Ragdolls were fairly new at the time and they generally added proper weight to the models in this game. Only gripe I have is would've liked a skybox that resembles the skies seen during loading screens. Not a big deal.
Sound: Guns sound like guns, explosions sound like explosions, lasers sound like typical lasers in media, and usually distinguishable from one another. Soundtrack is pleasant enough that it doesn't exactly butt in. Voice acting isn't bad either! Minor complaint, all of the soldiers really sound as though they're sick of your crap.
Story: Not much to say that isn't spoiling the major plot points that you uncover, but seems pretty well-written and thought out. Gist is humans escaped earth on colossal space colonies/prisons? called Laputas, they decided to try and reclaim the earth, and they find it's a total mess.
Mechanics: Without referencing other games, which is often lazy, on missions it's a squad-based real time strategy that you can pause and speed up/slow down as needed. Outside of missions, it's a lot of base management, politics, resource balancing, and land grabbing as well as development. And I'm talking a LOT of base management, it's really quite complex, not for the feint of heart, but pretty rewarding how much depth there is. Using other games as reference, missions play similar to Fallout Tactics or X-Com 3: Apocalypse's missions.
Buyer Beware: Probably the biggest issue I'd like to mention is that it's buggy. I recall it being buggier in the past, not sure how buggy it is at this point, but there's content that's in the game that doesn't work like what it says on the tin.
Overall: Quite enjoyable, and quite fun, bugs aside. Might be a little needlessly complex for some, the price is absolutely right as well. If you enjoy this one, you may enjoy the somewhat less complex UFO: Afterlight, which takes place at the same time, granted the visual aesthetics are a bit different.