I've just got this as part of the MacUpdate back to school bundle and, although the premise and features are great it is too buggy to earn more than 3 stars. Sharing by e-mail just doesn't work (which, as I am using MobileMe, is somewhat unforgivable as this should be the easiest setting to use) and there is zero feedback as to why other than a beep which doesn't infer any meaning. Worse yet, if sharing by e-mail is on, the app continuously uses greater than 100% CPU (on a C2D iMac), until it is quit and 10 to 20% when simply running in the background. Neither is acceptable behaviour.
I've marked down ease-of-use and stability because of this - if the problems were fixed then it would be a 4 star app, easily, as the features can't be faulted. What is particularly good is the ability to set activation regions for capture rather than having the whole view trigger photo taking. This means you can set areas that you won't trigger yourself through normal use. There is however, one exception and that is the sharing to .Mac - we should be able to lock down the folder the photos are uploaded to and the site to view them (otherwise it is trivial for someone to find images of the inside of your home and/or remove the images).