Bullets fly in fantastically complicated action sequences where you're half enjoying the suspense and thrill, half trying to figure out the logistics. Also, there's this really great effect where anyone who gets shot emits a kind of red cloud of blood, which is awfully pretty.
But what I really adored about the movie was its wonderfully sentimental side - it's a really touching depiction of a gang of guys who adore each other. There are some marvelous scenes where they're just playing around and having a great time, as well as some really poignant emotional moments.
A great movie. I found myself getting more and more absorbed in it as it progressed, and loving it more with every passing moment.