I have the GPS version since launch day, really haven't missed the LTE.
The LTE gains you a sapphire screen, and 16 GB over the Ion-X screen and 8GB
The storage will probably only come into play if you want to store more music on the phone.
as far as operation, If you're close to your phone, or in a place with a known** wi-fi network, the 2 will operate exactly the same.
The LTE version will allow you to connect if you're away from your phone, and there's no wi-fi
**You can't browse or select wifi networks to join or enter a wi-fi password on the watch, but it will join networks you've previously joined and stored the password for on the phone. The watch also is not able to present a wi-fi log in screen for you to click on, like you would find in a hotel.