Even with the new races and units, it's starting to feel a little recycled.
New Races:
Soulstorm adds two new races bringing the total number of races to 9. Which compared to other RTS games is a hell of a lot. Although eyebrows were raised when the two races were going to be the "Sisters of Battle" and the "Dark Eldar".
Unlike the Tau and Necrons added in the previous expansion pack the two new races aren't that much different from the ones already in Dawn of war. The Sisters of Battle are basically an all female version of the Space marines only a little bit weaker. The Dark Eldar don't add a lot of variety either. There units are either excel in hand-to-hand combat or ranged combat, which is the same story with the Eldar. While both races have "special" abilities (The sisters of battle have to build Holy relics to acquire "faith" which powers some of their units special abilities, and the Dark Eldar harvest souls from the dead to unleash special abilities.) It doesn't really add anything that will make you go wow or effect the way you play.
Considering that a lot of Warhammer 40k fans have been crying out for the Tyranids to be added since the first expansion pack it's a bit of a cold shoulder from THQ and Relic that they haven't added the Tyrandis yet.
Gameplay:
With the main solo campaign Soulstorm has taken and expanded the gameplay from Dark Crusade. In Dark Crusade you battled across a single planet Risk style. All races would take it in turns to attack adjacent territories. With Soulstorm the idea and gameplay is the same except that it has been expanded over 4 planets and 3 moons. Although by doing this it has only roughly doubled the number of territories it does mean that there are now at least 35 to battle across.
I can see this becoming a Marmite situation. You either love it or hate it. Some might be happy they've kept the style of play while others may feel like it's a re-hash. And those who didn't like this style in DC aren't going to see it return on a much grander scale.
There is also another problem with this style of play. In Dark Crusade when you conquered a territory all the structures you built were saved, so if you were attacked you'd start with all the buildings you had from previous plays on the territory. But for some reason in Soulstorm you don't. It may not sound like a big problem but its annoying having to rebuild everything from scratch over and over again plus it puts you at a big disadvantage if you are attacked by a large army. This normally turns into a race to raise some sort of army in the time it takes them to cross the map.
I've also noticed a bit of pathing problem as well. Units for some reason or another will become "stuck" and just move back and forth slightly. It's easy to solve this problem but when moving units long distances repeatedly it can be slightly annoying. Plus this problem wasn't present in previous versions of Dawn of War.
New Units:
Now my biggest complaint about Soulstorm. The new units.
For some reason air units have now been added. This is an odd decision as not only are there plenty of ground units to add to each race but before the games release relic held a poll on their website asking people what units they wanted adding to each race. None of which included any mention of air units.
In my opinion the air units are pretty useless. They don't really add anything new and considering the vehicles already available are pretty expensive and weak. I've also noticed that when i play a skirmish against the PC, they hardly ever build them.
Misc:
On the graphics front the game hasn't really changed much. Some people might like the style of the units but for me it's starting to look dated, especially when you zoom in to some of the basic troop units.
In regards to the sound not much has changed. The units, as always, have great quotes when you click on them or give them an order. It's a minor detail but one i very much like and something i think makes the units come to life. Although saying this, the banter between some races in the campaign mode when you're invading their main base is missing.
Summary:
To sum up Soulstorm is a solid expansion pack. It ups the number of races to 9. The gameplay is solid, fast and enjoyable. Is great to play online. And it still manages to keep the feel of the Warhammer 40k universe.
However apart from the races it doesn't really add anything new. Which is great if you love the previous expansion packs or if you're a first timer but for me it's starting to wear a little thing, especially when you consider how the previous expansion packs made big changes to gameplay in one way or another. Also the new units are a complete waste and you can very easily go through a whole campaign without using them.
While Dawn of War is still a fantastic RTS i think Relic/THQ needs to move on. They can look back at Dawn of War and the expansion and be rightly proud of what they've done but they need to put it all to bed and start anew.
They need to make a sequel with a better graphics engine (Company of Heroes showed us what they can do) and somehow reinvent the main campaign gameplay to make it feel fresh...and add the Tyranids as a playable race!
So to sum up, i can easily recommended Soul storm to new gamers and to regular players of the series but with the latter i would warn them that they shouldn't expect anything radical, even with the new races. But it somehow still manages to stuck you in, which is a sign of good game to me.