I also get about 40-44 hours on my original 42mm watch. Doesn't bother me because every other night I remove the watch and put it on the charger. My iphone 6+ gets about 3-5 days mostly with wifi connection as I'm home most of the time.
I believe that as the watch gets more use with more features and apps, the battery life will be less, not more unless they figure out how to make the electronics more efficient. I don't believe there is a more powerful battery technology on the horizon so we're stuck.
My suggestion to Apple was to work on solar recharging to extend the battery. The solar cells could occupy the entire wrist band for added power.
I can't say I get anything like that. 2 hours on the bike and it zaps 40% of battery. An hour walk takes its toll. I usually make it through the day, but always put it on the charger for 20 min or so after a long exercise session. Love the watch, but battery life since OS3 has not been stellar at all.