I have a Pebble Steel (original, not Time) and, for me, it ticks all of the boxes.
First of all, I actually like the "Industrial" look of it. It doesn't look like girly bling, like a certain other smartwarches.
played around with a variety of apps and functions on it, but the feature that it is most useful for is notifications. A quick glance at my wrist and I can see if its something I need to deal with. It does this as well as any other smartwatch, but without their inherent downsides of poor battery life and normally off display.
The always on display is clear and means it doesn't really look like a smartwatch. The battery really does last 7 days and it really is waterproof. This, pretty much, means I can treat it like a "real" watch in the way I wear and use it.
I like the wide range of 3rd party watch faces that are freely available. Currently sporting a LCARS style face. Nerdy but actually looks rather nice.
The "Cloud Pebble" development environment is rather neat. It works well, is well documented and means I can knock up apps and faces wherever I have access to a web browser.
Essentially it is a watch that is "smart", rather than the micro-fondleslab on your wrist that the more "upmarket" smartwatches try to be.