It's AMOLED. I can get somewhere between 1.75 and 2.75 days, depending on how much I actively use it (and presumably, how much my movements cause the full face to light up). According to Watchmaker, my face has an OPR [1] of 5.5% bright, and 1.3% dim (idle) mode, and I leave it in 'always on' mode (where it is in the 'dim' mode most of the time). If you use a watchface with more stuff on the screen, battery decreases. If you change the face to turn off instead of dim, you get a lot more.
I've never had trouble getting through a full day and most days it has 50-60% left. If I'm not wearing it, I stick it on the charger (magnetic) which is always sitting beside my bed. I will say if I travelled a lot, the extra hassle of worrying about charging it and not forgetting/losing the charger would probably make me not bother with it, but I only am away for more than a night a handful of times a year (and either bring the charger, or wear a different non-smart watch).
I've never had trouble getting through a full day and most days it has 50-60% left. If I'm not wearing it, I stick it on the charger (magnetic) which is always sitting beside my bed. I will say if I travelled a lot, the extra hassle of worrying about charging it and not forgetting/losing the charger would probably make me not bother with it, but I only am away for more than a night a handful of times a year (and either bring the charger, or wear a different non-smart watch).
[1] https://plus.google.com/102436534884531510368/posts/R2878L81...