Well the singel player is the worst part of the game and some times bad because of frustrating waves on waves of enemies....

I also enjoyed the Single Player part. It doesn't have a ground breaking story or plot, but there is a good amount of nice action in it. I don´t recall how long it took me to complete it the first time, probably around 10-12 hours i think, but again not sure.

Single player is good. It's about 12 hours and the harder difficulties can be a real challenge. There are a good amount of change in scenery to show off the graphics and they sprinkle in some fun vehicle (tank, mechasuit) action.
 
And yes, you can set up multiplayer matches with bots only.

" Well the singel player is the worst part of the game and some times bad because of frustrating waves on waves of enemies.... "

I enjoyed it.The single player was fun and the multiplayer was ok,I'm not sure how I felt about playing multiple game types EVERY game,but it was still fun at times.Haven't really played it in a few months though,so.My biggest complaint was the feel of the controls,aiming just felt weird,I still don't  know if it was the game or that funky ass PS controller.

It's easy or challenging depending on what difficulty setting you put it on and it's plenty long so yeah don't worry about it man just play it

It's all around awesome game, it's pretty challenging on the last 2 difficulties, but the other two arnt to bad.

The campaign was fantastic. One of my favorites.

Multiplayer is better than singleplayer. I have nightmares of Rico screaming 'mother fucker!' over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over.

" So i just ordered killzone 2 for my PS3. Ive played it at my friends house and i know its amazing but right now i have no internet connection so i cant play online, is it still a good game without online play?, how long is the campaign? and is it shit easy or challenging??, answers wouls be appreciated. "

I didn't find the campaign to be all that great.  The level design didn't really make for strategic combat, and the environmental aesthetics made you feel like you were in same area throughout the entire game (save for one desert location).  Also, aside from the bolt gun and the "lightning gun" (forgot its real name), the game doesn't have the largest variety of weapons for you to use effectively in different combat situations.
 
It isn't a bad single player game though.  I just thought that KZ2's multiplayer is where the game really shines.  Still, if you can find this game for $30, or if the game is on the Greatest Hits list, you should pick it up.

" But Rico's dirty mouth is what makes it so awesome! F*%$ you motherf*!$#ing Higs!  "

Killzone 2 was the first game I bought when I first bought my PS3. Took me a while to get used to the controls, mostly because I hadn't touched a Playstation controller in almost a year till then. The campaign is good but I found it too shallow for me. 
 
The story is invisible, it's pretty much-- you go down to the planet, and YOU ARE THE ONLY ONE THAT CAN STOP THEM! I have no idea what's going on, why we are there, who anyone is, I don't even know who I am. Sure the NPCs shout at me and call me by a name, but I don't know what the character is all about, what his motivations are, or goals. There's no exposition, eventually I gave up on the campaign as it seemed to be a waste of time, again, I didn't know what our ultimate goal was, "to win the war?" I need something more concrete than that to keep me motivated.
 
Try Call of Duty 4, that game did well in that regard...well in almost all regards but it kept my interest from beginning to end. "Get to this base or else the entire Eastern seaboard is gonna be nuked!" Okay, now I'm motivated!
 
I never played the first Killzone, so maybe all my questions are answered there, but they could have at least put up a scrolling text box that gets me up to speed. 
 
The game also tends to just shove seemingly endless waves of enemies at you making your movements very slow, and boring at times. 
 
You can be taken out very easily, but your enemies are freaking bullet sponges, most of the time it would take almost half a clip to kill one enemy. Couple that with your health regenerating too slow for my personal comfort.
 
 Does it make the action intense and nerve racking? Absolutlly. The game's not hard, it's just frustrating, if that makes any sense. It's not bad, but my goodness it can feel like a grind. 
 
The multiplayer is a lot of fun, but again, I come back to Call of Duty 4, it just doesn't have the in depth customization for your weapons and skills like in Modern Warfare. The maps are large, sometimes too large, most of the time all the action is held at only a section of the map and the inability to spawn at multiple points means that there's a hell of a lot of running back to said section to get back into the action.
 
 I'm rambling, it's a good game, but there are better games out there, that have a longer lasting appear.

" @ScrubbingBubbles said:

" But Rico's dirty mouth is what makes it so awesome! F*%$ you motherf*!$#ing Higs!  "

Glad they made Rico. That benighted lamebrain is the perfect example of how American troops are easily brainwashed by media propaganda.  Yes, I know I will be getting hate mail for my opinion. Sometimes I wonder what happened to free speech or that people are entitled to their opinion. "

" @Alphiehyr said:

" @ScrubbingBubbles said:

" But Rico's dirty mouth is what makes it so awesome! F*%$ you motherf*!$#ing Higs!  "

Glad they made Rico. That benighted lamebrain is the perfect example of how American troops are easily brainwashed by media propaganda.  Yes, I know I will be getting hate mail for my opinion. Sometimes I wonder what happened to free speech or that people are entitled to their opinion. "

Or you're just an obvious troll. "