Underwhelming
Ok, so I obtained this... it's ok. Not the sort of amazing experience like Company of Heroes or Sins of a Solar Empire. It feels just as wacky as the other Red Alerts, the movie cinematics are definitely the strongest selling point for this game. I couldn't help but feel very cramped and claustrophobic with the camera, I kept trying to scroll my mouse so it would zoom out, but no dice. That's kinda a personal preference though, so you guys might not mind.
The other thing that I noticed is that this game seems to have very hard counters. For example, you might be used to say, Company of Heroes where you can use a Tiger tank and pretty much throw it at the enemy without too much worry. However in RA3, if you use the wrong unit against an enemy unit, you're gonna get your ass waxed very quickly. Don't be surprised if your army of Mammoth tanks gets wiped out in 30 seconds or less. Something that's compounded by the fact that there isn't much real estate to work with on the maps. I found the units very big and hard to manuever around all the buildings sometimes. This only compounded the feeling of being cramped.
The co-op feature in single player isn't very interesting, you just get an AI teammate that has his own base and units following you around and helping a little. Nothing ground breaking.
For me, it's an average RTS. RA fans will like it, but the gameplay really isn't as fun as the cinematics, they're the best part of the game.