I would say the greatest difference between soccer and the sports that seem to be popular in the States is the frequency of scoring, really.
As a general rule, most sports popular in the US are sports that are eventful all the time, generally with many goals/points to be earned and few ties. In basketball, there's scoring every single minute, whereas a match of soccer can end with 0-0.
I don't really watch sports on the television, but soccer is probably my favourite sport to play with some friends. I appreciate the system of soccer. You can work for half an hour, or even an entire match, for a single goal. The rush when that goal finally hits the net is enormous, whether you are playing or watching the game. Well, not the watching in my case, but that's what I see with most soccer fans.
When you compare that to, say, basketball, you'll generally have a game with a lot more events and almost no chance of a really boring match (soccer, on the other hand can be terribly boring at times, if the teams are not playing well). The downside is that scoring just doesn't seem to matter. To me, watching basketball is like watching a slow-paced, boring game of soccer. Huzzah, another goal, one of the fucking 70 goals in the match. It's so eventful that whatever happens doesn't really matter, nothing really stands out. The only time when it can get exciting is when the scores are near-equal at the very end of the match, the only moment where that one goal actually does matter.
In the end, the difference is not that enormous. Do you like the few oasisses of excitement that soccer gives, or do you like to be satisfied with some action during the entire game? I prefer the former, but I can certainly understand people who prefer the latter.