Pros Reasonably fashionable to wear with cuffs. Allows for solid voice integration with Siri for appointment setting, sms reading and reminders. The wrist vibration feature is really handy when your phone is on mute and in a bag.
Cons Not water proof. The LED display is a bit small for a quick look. It would be great if it could share notifications with a few additional apps (IMs, etc) and also if you could sync more than one email address.
Summary Overall, I think this is definitely a step in the right direction. Easy to setup and use, I have quickly found the Martian watch to be a helpful (and fun) tool.
Pros 'comon? Really? If these catch on, will it really be inconspicuous for everyone to be sitting in a meeting looking at your wrist and no one will be the wiser? Really?
Cons Why not just strap on a smart phone to your wrist? It's not much bigger than this monster watch.