I completely agree with you, but you assume that this device has capabilities that it doesn't. I wish I could edit my previous post, as I feel like it would be helpful to address at the top, but this will have to do.
Whistle Tracks:
Type of Activity
Duration of Activity
Whether or not the user holding the iPhone w/ Whistle app is near their dog wearing the Whistle (I'm assuming that's how it tracks who the dog is with)
Whistle Does Not Track:
Speed of activity
Distance of activity
Calories burned
Type of Sleep
etc. etc.
(getting this from the website)
So unless you're simply tracking "My dog ran for 2 hours at 3pm" in a spreadsheet, I don't see how this helps you. All those nice little statistics people track using a Fitbit or other tools are not provided here.
So to re-iterate (and not harping on you bradleyland, just for the benefit of the majority): If you are a attentive and interested dog owner you probably already know the activity and duration of your pet. Intensity of said activity would be quite useful, no doubt. But that is not provided by Whistle. Location of said activity would be useful. But that is not provided by Whistle. Distance traveled during said activity would be useful. But that is not provided by Whistle.
If there was, say, a Whistle with GPS, accelerometer, heart beat monitor, etc. (possibly something that measures skin excretions?) it would be fairly useful. This is not that device.
edit: Downvote brigade is out today! I would appreciate it if you would let me know how I am wrong instead of simply voting me down. At the very least it prevents me from looking like an idiot and allows me to retract/modify my statements
edit edit: On further reflection, this could create some false data. A dog chasing it's tail for 2 hours in a kennel could be recorded as meaningful exercise ("running for 2 hours" according to the Whistle), leading you to make decisions off bad data ("I have no idea why she is so hyperactive, she get's plenty of excercise!"). Maybe. Just a thought.
edit edit edit: A nice analogy... Whistle is the Moves app for Dogs. Except it costs $100 more and requires extra hardware.