Among the best squad shooters ever.
The gameplay is very good, with solid controls, pretty good AI, and awesome physics. The squad controls work well and are simple enough that anyone can get them before the training mission's over. The weapons are also well done, especially on their respective ranges, an issue in some shooters. Carbines are good up close, rifles are better far off, snipers are amazing at range, but have low fire rates. It's all very well done.
The graphics, too, are incredible. This game absolutely makes the most of the PS2's hardware. The characters are super-detailed and animate nearly perfectly. The backgrounds and environments are great, as well.
The sound is also good. The weapons all have excellent reports and the voice-overs are great. The music also does a good job of pulling you into the action.
This is a game that'll last you a while. With three mission arcs, several sub-missions, and higher difficulties to unlock more guns and other things, you'll be working on this for a bit.
In summary, SOCOM 3 is a truly great PS2 shooter. And even if you don't want to buy it just yet, SOCOM 3 is worth every cent of the 5 bucks it takes to rent.