I have this. Actually, I was saving for Mirror's Edge but apparently the pc release was moved to January so I bought this one instead.
It's a good game, much like tiberium wars. Excellent (and sometimes funny) cutscenes with great actors/actresses. Battles at sea takes a big part now since pretty much all units are amphibious. Most buildings can even be placed on water! All units also have a secondary attack now, like the attack dog, you can use his ability to howl and stun nearby infantry so that he can eat them all (or not). Campaigns are pretty much fun now since they added a cooperative mode which you can go online, connect to gamespy or something, or just have the AI help you on missions. The Japanese are also a nice addition to the battling forces.
Apparently the gameplay was halfbaked, the units' pathfinding is horrendous. If you order them to point b from point a and there's a wall between, they won't try to find the nearest pathway, but instead they just push their luck to break the indestructible wall to go through it. Resource gathering is also 1:1 now, meaning 1 gold mine = 1 miner. They removed the gem collecting and replaced it with a goldmine which is much like in Warcraft 3. And also, many units in RA2 never made it in RA3, prism tanks, chrono legion, desolators (my fave), crazy ivans, etc.
And oh, all commandos are female.
