Some people don't agree with the 'open hard and fast' rule, but I think it's a great way to get into a story, especially when the reader hasn't met the book's characters before (or heard of the author).  That said, I don't think that means every opening must include murder, mayhem and/or explosions. 

To me, 'hard and fast' means grabbing the reader by the brain within the first few paragraphs.   By sparking our curiosity from the very start, a good writer pulls us into the story before we know what's happening. Here are some great examples: 

a)     “Where’s Papa going with that ax?”  Charlotte’s Web, E.B.White

b)      “How much of this blood is his?”  Chainfire, Terry Goodkind

c)  The last thing I wanted to do on my Summer vacation was blow up another school. 
                                                                                    The Battle of the Labyrinth, Rick Riordan

d)      Bailey Wingate woke up crying, again.  Up Close and Dangerous, Linda Howard

Sure, the rest of the novel has to live up to expectations, but you only get one chance to make a first impression, so we ought to make it count.  Not all books hit the page running, but I'd say they got published despite their slow start, rather than because of it.  Of course, that's just my opinion, others may disagree.