It's still really expensive, which is why it took me so long to finally buy it, although it's cheaper if you don't get the digital display. We can see how THAT plan went, though.
You strap it on, and it somehow takes four different measurements to calculate calories burned. It does it when you're sleeping, too - assuming you WEAR it when you're sleeping. Otherwise it guesses based on the other measurements throughout the day.
So then you upload the info to their site, and it shows your calories burned so far that day (or for multiple days), how many calories you'll burn if you do nothing else all day, etc. It also graphs it out so you can see how much you burned in specific time periods.
Then you log your food on the site (this part is annoying if you're used to a better site, like The Daily Plate) and it keeps track of that, too, and calculates your calorie deficit (or surplus) for the day. Plus it gives you the nutritional balance (carbs/protein/fat), but it doesn't include as many nutrients as TDP does (just the basics, plus sodium and calcium).
Before all that, of course, you put in your personal info and your goals, and it gives you targets (for calories to burn and calories to consume), to maintain the balance you need to meet your goals (a 500 calorie deficit each day if you want to lose a pound a week, etc.).
And then you also get a phone coaching session. I'm not sure what happens with that; they said it's better to wait two weeks to do it, so they have some data to look at when you talk to them). Mine is scheduled for a week from Friday.