A reviewer indicates the GPS tracking is only modestly accurate. So the walk measurements might be a tenth of a mile off.

The more fundamental question is, do I need walk tracking? I roughly know how far I'm walking. Do I need a sleep monitor (whatever that is)? Will it help my sleep? Do I need a step counter? No.

Seems the only real reason to get this over a basic watch is to have some numbers to look at when I'm bored.