I have the original, (gray, with third-party leather band,) and think it's great. Battery lasts 3-5 days on average for me. My wife
really likes it - I no longer pull my phone out of my pocket (or pick it up off the table,) all the time when at dinner or out somewhere together. I just glance at my wrist. (I am often on-call and need to pay attention to email 24/7.) Makes for a happier marriage.
Would I like a "more capable" watch? Sure. But the Pebble is light, battery lasts sufficiently long, and does enough to be truly useful. I don't think I'd buy an iWatch unless it has at LEAST a 3-day battery life (always-on, I can't stand the "screen off" nature of the Galaxy Gear,) along with noticeable enhanced functionality.
The ability to have basic functionality without being connected to my phone is also good - yeah, I can't do any internet-connected tasks, but I can still use offline apps.