In more than a few ways, B Button is similar to Forest Gump. Both have you almost believing in the unbelievable premises as well as being films of adventure and discovery.
There are even character similarities, Captain Mike in this film draws heavily from Sgt. Dan in Gump, and, at least for the first half of BB, the title characters both have that certain innocence as they take in the world around them.
BB is beautifully filmed, though it does go on a tad too long (some judicious editing may have helped as it's not so much a question of pacing as it is the story getting bogged down with too many sub-plots). Regardless, the final pay off is worth the wait, and the final scene of Katrina flood water rushing towards the abandoned clock is masterful, especially as the clock again begins its relentless run backwards - suggesting that we all wish we could turn back the clock on that disaster, ignoring the BS from the army corp of engineers and refitting the levees.
The story is based on a F. Scott Fitzgerald short story of a man who ages backwards (starting as an old man, and ending as a child). The film does an adequate job of showing the reverse ageing, as well as a fair job of reminding you that mentally he is ageing properly, from total innocence to... well, let's just leave that to your imagination.
Brad Pitt doesn't really have to do all that much as the lead, except be Brad Pitt and carry the 2nd half with his presence, which he does well enough to warrant star billing.
There is built in pathos in the 2nd half of the film and it serves the film well - overcoming the oddly wooden performance of Cate Blanchett, who as an adult flips back and forth from ice queen to something with a quiet depth, though too much the ice queen - quite the opposite of the mischievous young girl BB first meets. There's an entire sub plot concerning BB's real father, which frankly the film could have done without as it really adds nothing in the way of drama or anything else for that matter.
The film's gimmick storytelling works to a point, though at times gets in the way of the story being told, and I must confess I often had difficulty understanding Blanchett when she wheezed her lines as an old dying woman - combining that under annunciated whisper with a southern accent was just too hard to comprehend, making this a worthwhile view, but not a film for the ages.