I've owned this game for about 4 years now, but this is the one game I cannot get enough of, no matter how many times I play. It is nearly perfect in every way, and still holds well.
The story mode is highly creative, detailed, challenging at times, and just plain fun. Onslaught and the addition of vehicles is addicting, no matter if you're playing single player or online. The main thing I love about this game, is that the graphics are great for the time it came out..and still holds true today. However, the best part about the graphics.. is that you don't need a huuge cpu, or graphics card to power this game. Everyone should own this. I love the expansions, maps, skins, just a ton upon ton of stuff you can find on the internet FREE of charge. It's like getting a ton of different games with this one.. so the value is amazing. Online is where this truely shines. an onslaught 32 player map, and this Invasion RPG elements added a ton of lasting value.
In conclusion, if you like value for your money, and you like to see alot of content. This is the game for you.
EDIT (10/27/2011): I didn't think anyone would actually read this review. I believe I had either had the written just before the star rating was in place (aka launch of the siteish) or, I completely missed it... more than likely the latter. Anyways, thanks for bringing this to my attention. 5 out of 5 should have been the rating.
Also, sorry for the editorial skills, this is more of a rant praise with no proper structure than anything.