The Pebble watch will work with both Android and iOS, for starters (but then again, so does Android Wear devices now too... leaving just the Apple Watch to only support Apple products).

It's SDK is in Python or C, and it makes it really easy to write up basic apps for yourself or others (no special hardware, licenses, or fees necessary to start developing your own apps).

Battery life kills all other smart watches. The always on screen is very nice too (makes it usable as an actual watch, for instance).

So called "Smart Straps" allowing 3rd parties or the OEM to produce different wrist straps capable of different functionality (sensors, additional battery, etc...) - And they are swappable/upgradable.

I had a Pebble Time and put a number of months into using it full time. The screen is a color e-ink display that is always on, which is really nice. When I chat with my Apple watch friends, the biggest gripe is the battery life. With my Pebble Time, using notifications and using it to respond to text messages, while wearing it all night to monitor sleep, I charge it about every 5 days for a couple hours.

Everyone I know personally with an Apple Watch complains that the battery hardly lasts a day and they're forced to basically charge every night, which I guess gets annoying.

Right now, I think the battery life thing is a major issue with smartwatches like the Moto 360 and the Apple Watch. The Pebble models, the Basis models, and the Garmin models all seem to have this ironed out.

Obviously this is just a personal preference, but the Apple watch is ugly. The Moto 360 was the only other watch that I think that comes close to not looking like a smart watch.

Also the e-ink display is a different strategy. I hate the the watch display isn't on all the time so you can't just glance at it without moving your arm.

They use an e-ink display for one which means a week of battery life(or 2 days in the case of the round).

That's like comparing a Fiat to a Porsche.