This in short is a great piece of design. Especially coming out of facebook this is amazing (well they now have one of the most talented designers so not that surprising). However, as a business this is killer and shrewd. Everyone would want to save a log of their life. More app permissions to add to timeline > more auto posts in ticker > more connection for Facebook. Well played! Disclosure: I am working on somethin…
At the time I think I got too caught up on the idea of it being all my own data. You could easily make it pull in data from Facebook (as well as your own data and other places). I think the gain of a dedicated app is that it won't change when the next idea for a profile comes along. Also, you can probably do an even better and more useful job if that is all you are focussed on.
Good luck!