I've talked a good deal about Swat4. I've named it my best coop of the year 2005 and, by the looks of it, i'm going to have to name it best of 2006 too, unless something really good comes out (hint: Armed Assault).
So i've been playing the TSS expansion, and let me tell you that everything that was right and great about Swat4 is back, only bigger and sweeter. The maps are bigger, the ennemies meaner, the civilians less cooperative.
I don't mena to sound rude or anything, but this time around you can actually hit them civilians' with your "Fist of Righteous Fury". That's right, hitting them to calm them down and get them to cooperate is now an 'option'. Oh! and sometimes the bad guys actually answer to that (things like: "you sister liked it when i did the same thing to her last night")
Back to the coop gaming. There was a hack that allowed to play coop up to ten players in Swat4, and Sierra has now wisely decided to make that official, so 10 players coop is now an option. To go with that you also get bigger maps that will keep you busy and looking in every direction.
So YES, the expansion makes Swat4 even better than before. If you have Swat4, don't wait no more, and if you don't get the gold edition that marges the two together. You will enjoy new weapons, new maps, and generrally speaking a better game.
Now, supposing you get tired of playing cooperatively, and feel some "edge" is needed, try playing the other mods of Swat4, including team versus team (barricaded suspects). Swat 4 was designed for small teams to meet and shoot each other down, and it shows. To have actual fun, DO TRY TO PLAY WITH THE NON-LETHAL WEAPONS for a round or two. Tell me what your best moment was when you tried it. I know you never thought that arresting people could be fun, BUT IT IS. For real.