I hate to say it, because they're local here in Kansas City, but I'd stay away from Garmin if you want your device to integrate with anything else. I bought a GPS of theirs last year. I've never experienced frustration like I did trying to download a map from the internet and put it on this device. I now have SIX Garmin applications on my computer that I have to use to manage the device. (I'm not kidding.) Garmin BaseCamp, Garmin Express, Garmin MapInstall, Garmin MapManagaer, Garmin POI Loader, and Garmin Web Updater. Every one of them is buggy and hard to use.
Wow. That is awful. I use their fitness devices (Edge 500 and one of the ForeRunners) and they've had some issues (bugs in the firmware), but nothing like that. Both integrate with Garmin Connect (the web site) using the Garmin Express app (OSX).
If that did sleep and activity tracking, then I would be in. Also, I didn't see battery life, but that might be an issue also. All I want is to log my heartrate throughout the day via my phone along with good sleep tracking. I'm ok with wearing a heart rate band.
While it isn't a true smart-watch, it does provide alerts from your phone. I imagine for many users, that's enough.
If I hadn't stopped wearing a watch completely a few years ago, I'd probably buy this one.