Death i've been to the last US held WC and the Germany WC and both times had some of the best experiences ever. Even if you don't like soccer it's something you have to view in person at least once in your life, especially the Brazilians. I was Palo Alto for the US vs Brazil game and talk about a classy bunch of people. They want to always give you food and drinks and always just enjoy the game, not to mention some of the ladies are just down right gorgeous. I hung out alot with the Brazilian fans during the Germany WC as well and still keep in touch with a bunch of them via email(though their English is rough and my Portuguese is even rougher).
Soccer is more of an acquired taste and takes a lot of skill. It can be fast paced but normally it's thought out and strategic in a way. Nebraska was never really huge on soccer when I was a kid but moved to Nevada and it was a large following. I've played since I was 4 and continued through college, unfortunately after the Marine Corps and my 2 ACL repairs, i've been sidelined and will coach my daughter here in a few years.
All in all, this is one event I recommend to anyone and everyone if you get the chance. You think fans get riled up at football games? Football games have absolutely nothing to compare with soccer games in that aspect. If you can't make a WC game but can make it to England, try to catch a premiership game, they come a close second.