Best in series!
Now looking at this from a block buster, big budget, hyped, $60 release I still found it quite entertaining just not enough to blow my socks off per say.
Hands down I want to say that this is by far the best game in the series. Killzone was nothing special to me at all, Killzone 2 was an average romp around the FPS world and finally Killzone 3 has pulled it together enough to hit nearly every necessary check mark required today to make a solid FPS. Killzone 3 doesn't really push the envelope past other top FPS franchises but it does some of the same things very well indeed.
The story in Killzone 3 was actually fairly entertaining, enough so that I watched all the cut scenes and at times probably had my eyes wide open like deer in the headlights, hard for any game to do might I add. Characters were memorable, destruction was on a massive scale and the brutality was in fact quite brutal. The campaign was possibly a tad short especially if played on easier difficulties, but the solid multi player should make up for that.
Graphics looked superb for a PS3 title on my 60" LED, explosions grand and settings varied enough to not bore. I did notice some frame lag when things got really explosive but not enough to ruin anything game play.
If you consider yourself a gamer there is no reason not to play this title, best in series and today more than worth what you pay at retail stores.