Socom can't even really be compared to any other shooters. It is the only one that needs to be played tactical to win. If you are playing against even mediocre opponents who are using team work, they will destroy you without a game plan.
All of the ranked games are non respawn, with many different game modes.
1. Elimination (pretty much team death match)
2. extraction (seal team must grab hostages from the other team. Then they must take them to the extraction point. If either team kills the hostages, that team will lose)
3. escort (seals must escort 3 V.I.P.s to an extraction zone, without the other team
killing the V.I.P.s In this mode the terrorists can kill the V.I.P.s and still win)
4. demolition (a bomb is in the middle of the map, and each team must grab the bomb, and plant it at the other teams base)
5. breach (the seal team must grab a bomb, and blow up entrance points into the other teams base, then they must plant the bomb.)
6. control points(self explanatory)
I think that is all the game modes. Socom is a much slower paced game then the others you mentioned. If you take off by yourself, more then likely you will die very quickly. To win games communication is very important. It will get you much farther then your personal skill at the game.
As far as the sound goes, in my opinion, no other game compares. If you have surround sound, you will love it. The guns sound powerful and tight, and the explosions are exactly how they should be, loud and powerful.
It sounds to me like the game is actually in 7.1. You can really set and listen where the shots are coming from, and pinpoint your next move off of that. One of the things I love, is the lack of background noise, other then what is actually being done in the game. Their are not many other noises, that are not someone actually firing a gun, or a grenade. It makes for some intense moments, when you encounter an opponent.
When the game first came out, it was a joke. The game was far from finished. I couldn't believe they released it like they did. Now though, alot of the bugs are getting ironed out, and it is a very good tactical online shooter.
I hope with the european release, more GTP members get this game. I tried to start a clan earlier, but there were only 2 or 3 of us in it. Hopefully we can get a better one together now.
The game will take getting use to, so don't get discouraged at first. I have been playing cod5, and tried out socom again the other night. I was horrible, it took me a couple of days to get the hang of it again.
This is a game that you will either love, or hate. The people who love it will never look at shooters the same again.
The people that hate it, will go back to COD, and their running and gunning.