Cataclysm has alot to offer for both Homeworld veterans and newcomers to the series, and is thus highly recommendable.
The story of Cataclysm takes place a while after the original's storyline. The Hiigarans made it to Hiigara- and are now busy building themselves a new empire, but not all of Hiigaran kind is doing all that well. One of the not-so-well-off groups of Hiigarans is kiith Somtaaw, and these are the guys you control in the campaign. The whole campaign starts when Kiith Somtaaw finds an alien artifact in deep space near Hiigaran space. Upon investigating the artifact, they end up releasing its contents, which happens to be a malevolent alien lifeform that comes to be known as "The Beast". So for the rest of the campaign, its up to you to lead Kiith Somtaaw in their efforts to destroy the being they let loose upon the galaxy.
Cataclysm's campaign is arguably better and more enjoyable than the original campaign since there is much more variety in mission objectives this time around. Its also just about the same length, though it ultimately comes off as shorter since many of those missions won't take you quite as long as some of the original's missions would. Its also a tad easier than the original campaign. The single player campaign serves as a very good way to get familiar with one of Cataclysm's two new races, Kiith Somtaaw. Kiith Somtaaw doesn't use any of the old Hiigaran ships, so their fleet selection is entirely unique. But that doesn't mean a veteran will have to learn how to use his fleet all over again, for many of the Somtaaw ships work similiarly to certain hiigaran counterparts. For instance, the Hive Frigate is essentially a more combat capable Drone frigate since it has its own weapons other than its drones. The other new playable race in the game is the Beast, who will be much more familiar to veterans since its standard fleet consists almost entirely of old homeworld ships. The thing about the Beast however, is that it can capture enemy ships and then disband them to learn their technolagies and how to build them. So if they captured a hive frigate with an infection beam- they could retire the hive frigate and then start building them. The two races give Cataclysm's skirmishes a bit more variety than the original's skirmishes, since the races are no longer carbon copies of each other. This alone is a great improvement, at least in theory. Thing is, the two seperate races here are for some reason not quite as fun to use as the original homeworld's fleets. Maybe its just because there are no super-cool standard ion-cannon frigates in skirmishes anymore (The Turanic raider ion-cannon frigate ain't nearly as cool even though the beast gets it in skirmish mode...)? Perhaps... Or maybe its simply because the fleet selection for both races is not quite as large as it was in the original fleets.
Graphically, Cataclysm uses the exact same graphics the original game used, so it looks great. The Somtaaw ships however benefit from higher detail levels than the original ships. The Beast's ships however are merely carbon copies of the captured ships with red stuff all over them, not very appealing, though the beast Mothership is an impressive sight to behold. Sound wise, Cataclysm uses the exact same sound set as the original, with the only exception being in the voice acting department. Cataclysm gives most of the new ships a unique voice over, and some of these voice overs can be surprisingly funny. The campaign makes very good use of the new voice overs as well. Its ultimately very effective, and a nice change from Homeworld's repetitive voices.
Ultimately, Cataclysm offers something for both veterans and newcomers. Both sides will undoubtedly enjoy the new campaign, and the skirmishes benefit from the new unique races. There are still a few problems, but Cataclysm is ultimately highly recommendable.
Pros: Two new unique Races. Enjoyable campaign. Graphics are still very good. Surprisingly good and occasionally funny voice acting.
Cons: New races aren't quite as satisfying as the original's fleets.
Recommendable for: Newcomers and Veterans alike should be able to enjoy Cataclysm.