I haven't fully reread this book since it was first released. It would be tedious for me to get into just why this book was a crushing disappointment when I read it the first time, so I won't. Other reviewers have cut into the context behind the seemingly-over-the-top reaction against 'Feast' I will only say that it was not over-the-top, 'Feast' can be that bad.
This volume introduced a flood of new character perspectives, broadening the scope of the story to a riverland devastated by Northern and Lannister armies, the Iron Islands, and Dorne. Were these perspectives worth a reader's time? Some perspectives established more back history to current events, gave another side to an already known event, and others padded out scenes between characters we never needed to meet in the first place.
Returning viewpoint characters spent their time ruminating over past events, reacting to past events, or traveling. Other than Arya. Stuff happens to Arya.
In this kind of series, no book is going to stand on its own, but 'A Feast for Crows' has no great centerpieces to it, no battles or significant events occur, (as I refuse to consider anything other than Prince Doran's speech at the very end of the book as worth noting, and don't even get me started on the damn Greyjoys) so it works best as a bridge between the books in the series. You read it to get on to the rest of the series, that's all.
Next: 'A Dance with Dragons'