Does the watch still have a lot of functions that work if I leave my house and leave my smartphone at home?
I am wondering how "tied" the watch is to my android smartphone. For example, what can I do with the watch when I don't have my smartphone nearby and paired to it via bluetooth.
You MUST have your phone with you at all times if you want notifications on messages, phone calls, etc. It wouldn't be worth much other than time without it.
If you want that functionality, look into a Samsung Gear S but be aware you will have to have a separate "phone" plan for the watch!