I finished Killzone 3 on the PS3 today.  I did it in three sessions.
My overall impression was it was time worth spent.  There are sections I really enjoyed:  there was a stealth jungle level that I really enjoyed (silenced sniper included!) and the snow jetpack level was great too.  I was  surprised how well I was able to control the booster pack.  I call it that because the jetpack does not work like Don West flying around some desert planet, but more like Buzz Lightyear:  'falling with style.'
The cut scenes seemed so unprofessional:  there were moments that were incomplete (How did I get here?) and others were very hurried.  The swearing was over-the-top and annoying.  
Malcolm McDowell did a good job as Stahl - the bad guy. 

They also introduce a new female character.  That's her on the left.  She calls herself Jammer.
I still like the realistic movement, but the cover system was useless.  I probably could have changed it in the options, but I miss the set up like COD for aiming-down-sights.  KZ is more of a from-the-hip shooter.  If you want to zoom in, you need to press R3.
I tried the multiplayer - well, not really.  They have a BOT version.  I figure I will cycle through the maps a couple of times to learn the system.  I have no clue about the character progression.

After playing only two maps, I began to wish I had more friends on PS3:  it was a lot of fun.  Since KillZone 2 beta, I have been playing what Guerrilla Games calls WarZone.  It is a cycle through multiple game types:  deathmatch, domination, capture-the-flag, assassination, and search-and-destroy.  The variety is great, but it makes for a long game.  I'll play that more.

I do have the PlayStation Move rifle.  I got it with the Resistance 3 Doomsday edition.  I don't know if I will go back and play it again with that 'casual' controller.
That reminds me, I gotta play R3!
And finally the ending - of the game that is.  Killzone 3 ends with a space battle - you are the gunner in a ship "on rails."  The result of the story, at first, leads you to believe that the war is over - I mean REALLY over.  But then there is a teaser for something more in the middle of the credits.  No teaser here, this blog is finished.