I guess this is how the franchise started.
The PS2 is probably my favorite system to date, and I just love going back to the huge game library, and this game is not a looker, even back in the day this game would not be placed in the in the top 100 polished games. The videos for the cut scenes look pretty pixelated, specially for a PS2. The in game engine seems to look better than the actual CGI, and the game itself it's quite lifeless in color, the textures can be very muddy and it can be hard to distinguish enemies from the environment.
The game mechanism it's enjoyable, I had a good time playing this game, but haven't tried the online multiplayer, and I doubt there would be anybody there, specially when you have the Killzone 3 in the market and probably another one coming up sometime in the near future.
If you would like to undust you PS2 and see where the franchise started you probably are going to have a good time.