I enjoyed the original game. It had a great story, nice designs and fun gameplay besides the bad voice acting, awkward controls and framerate issues. When I heard that the Killzone 2 demo was added in the Playstation Network, I downloaded it and played it straightaway it was actually pretty darn amazing. Here are my impressions:

The Good:

• Graphics are beautiful 
• Watching enemies fly from explosions and fall down from edges is satisfying.
• Perfect replay value.
• Smart and challenging AI
• Feels so immersive

The Bad:

• Bad voice acting (except for the ISA and Helgast soldiers)