If you're wife is a runner, do NOT go for an Apple Watch.
Some negative points I came across a while ago online:
- since it uses touch, you can't easily handle the device while running. That alone should be enough reason to go with something like Garmin that has actual buttons.
- the sport apps are meh. If you want a solid platform, go for Garmin / TomTom / Polar / other well known sport watch. Garmin is still the best feature wise.
- no always-on display.
- horrible battery life. Also don't think about using it as an alarm clock on your wrist to wake up, since you actually have to charge it every night or so.
I personally can't live without my Garmin's wrist vibration to wake me up anymore. Way better than a smartphone app beeping.
edit: Also, Garmin has an app platform. Just not as extensive as Pebble and mostly sports related.