mind if I start an argument? cool. SOF 2 is better.
Why? The AI is absolutely superb, the plot, whilst hardly being brain matter, is handled pretty solidly, the realism is well balanced. Although I have heard hundreds of people on forums wailing about how hard it is, but frankly its meant to be. If people can't keep up then they should stick to simpler games. MP is also excellent.
SOF 1, whilst being great fun to just run through wasting hoards of enemies, just isn't as advanced. It's certainly good though.