Agree with that - since having my Fitbit, plus the app and MyFitnessPal app, I actually managed to lose a significant amount of weight that I'd half heartedly tried to lose before, but never gotten very far.
Of course, that doesn't mean Fitbit etc is for everyone, but as far as i know a good number of people have had good results with it. As you say above, I found having the data right there that I could track a very powerful motivator.
We have a Sonicare brush, and its pretty great really. Probably won't rush out and buy one of these, but if the one we had dies, we probably would - I know every time I go to the dentist / hygienist I haven't been doing as good a job on the teeth at the back of my mouth compared to the front, and even though I know that, and know what I need to do, something like this could potentially be a good motivator in the way that Fitbit and the apps are. I didn't really need them to know that smaller portions and a bit more exercise would result in weight loss, but nonetheless making use of those tools is ultimately what I found gave me that extra motivation to really stick at it.