Today I took the watch for a spin. 1 hour to work, and then 6 hours after work, bringing me up to the present moment.
Everything generally went without a hitch. Connection stayed strong throughout until about 4 hours in when I noticed that the connection dropped twice in quick succession. I thought it could be due to weak signal so kept the phone close to the watch and lo and behold, problem fixed…
…Until I got in the car on the way home and the watch stopped working altogether.
When I got home I took it apart to find a broken solder connection in the wire of the strap. Well that explains everything.
A bit of solder and some hot glue to reinforce the joint and everything is back to perfect.
Still waiting to see how long the batteries last.