Where the designers failed, modders pick up the slack to create a truly epic space sim.
The combat was not that fantastic either. For battles that occur in space, the ships are fairly limited in movement. Even the fighters rarely ever perform amazing acrobatics of space flight. Instead, all ships fly in straight lines, never turning upside down or flying sideways for whatever reason. That was quite disappointing. Also, judging from battles seen in real life and imagined on screen, it's usually a non-stop explosion fest of everything going off everywhere at once. Here, the ships more or less take turns slapping each other with a white glove.
The two races are not that different, except in design, colors, and numbers. The Vagyr are much in the line of the primitive yet effective race, meaning they build quite quickly and their squadrons are larger. The Hiigaarans, on the other hand, have stronger ships, but come in slightly fewer numbers and are more expensive. Other than that, there's not much difference.
This game ought to get a 6.0 for all of that. However, thank God for modders.
The Homeworld 2 modding community has been hard at work on several mods that utilize HW2's unique space sim engine to create whole new worlds on a scale never before realized. The Star Wars: Warlords mod puts in everything from the universe and the kitchen sink and increases the numbers to create a frenetic frag fest of lasers, X-wings, TIEs, and cap ships just duking it out everywhere. The Dustwars mod seeks out to completely redefine HW2 as to what it could have been. Documents from its development reveal that a huge war was being waged in the Hiigaaran Empire, creating a much more epic storyline.
My personal favorite of these is the Point Defense Systems Mod, or PDS. It evolved from adding more defenses to cap ships and redoployable platforms to creating a more realistic battle space, currently at version 5. PDS goes above and beyond creating true 3d movement for all ships. So even the biggest ships can twist, turns, flip, everything. It also adds several more ships, increases the shots fired by a million, and you get a real sense of an epic war. In the distance you can see flashes of an ongoing battle and as you move in closer, the real details come out. And then as you follow a ship going into battle, you really feel like you're in the thick of things. I'm talking about lasers, ion cannon fire, missiles, everything all at once flying everywhere that you can't even tell what is firing at what. That is truly breathtaking and its sad that many war games refuse to go so far as to make the stake that insane.
So from the ashes of a mediocre game arises a truly frenetic example of what space war could be like. Wonderful, absolutely wonderful.