Almost as good as some of the mods.
Lordboogar wrote this review on .
The good news is that the overall production quality remains high, and the additional race is well crafted and has some interesting features. The rebalance tends to make the various races equally desireable although Table Top players may find the changes a bit contrived and heavy handed.
The campaign is not so hot- though this could be more of an indictment against the RTS genera as a whole rather than this game in particular. The focus of the game is it's skirmish and multiplayer modes, which are very replayable.
Before running out and buying this game however, I would recomend one of the excellent mods for the original such as Dawn of Steel, or Deamonhunters. These fan created add-ons are some of the highest quality third-party software around... the production value rivals that of the pubisher and these are also entirely free.
Last word: Winter Assault significantly changes the game in a way that improves the gameplay somewhat, but will violate the sensibilities of the Warhammer 40k fan.