Just finished playing the Breed demo and talk about lost potential.
Graphics: The graphics engine is decent enough. It does what it needs to do and you can see objects far away, no real performance problems on my GF3. It just doesn't do anything to help my jaw hit the floor. I had a few glitches with textures but I will let that pass on account of it being a beta.
So with a solid foundation like that they seemed to have gotten everything else wrong.
Sound: First off, the voice acting was so bad it wasn't funny. The guns sound pretty lame, some of the effects are passable, but generally not that crash hot all around. There are some effects that are so poor I could make better noises with my mouth. Also the demo lacked any sort of soundtrack, yes its a beta demo, but this really hurt the experience.
Gameplay: Well this is where Breed really goes wrong. It's just wrong. Your team seems to move at a snails pace, the AI is so bad that teammates can get themselves killed walking off a cliff into the water. The enemy AI comes straight at you, I don't think they even move from side to side. When you run your view moves from side to side and it's just plain anoying.
Summary: Don't bother downloading the demo, god it was so bad it shouldn't have been released. If this is anything to go by, the full version will be terrible. Wait for PC Halo.