Be cautious. It's hanging in there, but with new problems added. One step forward, one step back. Still very fun though.
Uprising added components to RA3 that were missing in the first place. This gives it a leg up to start with because it is improving the initial game. A clear example is for Empire players, who noticed that there were no anti-air (ground) infantry. There are a few good additions to the unit lineup, however, there are some units where you may think that the designers have gone overboard. Balance is something blown out of the water when the new units for the Allies and the Empire show up. A giga fortress for the Empire is incredibly hard to beat, even more so when it has reinforcements. The same can be said for the Allies new gunship, as if the Century bombers didn't have strong enough armour. It is a case of stalemate as far as rating the new units is concerned.
While new units are a huge part in any expansion pack and are largely responsible for my decent rating, the game does have some unforgivable issues apon release. Firstly, the co-op, nay the entire multiplayer section of the game has been removed. It is difficult to see the logic behind this, but EA have said that they have not forgotten the online gamers and are looking into adding a multiplayer in a patch down the track. The unique co-commander aspect of the original has also been removed. This is unusual, as that system was not cumbersome in any way. It was an extra tool to coordinate with your computer player in skirmish games, no matter how effective it was. Also, the pathfinding system is still very frustrating in that much of the time, it does not work.
Don't get me wrong, i still love this expansion pack and happily paid for it. You get to enjoy the game from different views from after the war, control a variety of new and unique units and you get to chuckle at Shinzo and his newfound hair. All in all, not a bad expansion pack, just as long as you are not expecting the world from it.