It's a great phone - there's no compelling reason not to get one unless:
- you are deep in the Android ecosystem
- you have unusual all-day battery requirements with no/limited way to charge during day (6S Plus or other phones with better battery life OR removable battery depending on your need)
- you really need stereo speakers
- you want the best camera (top Android phones and 6S Plus are a small, but noticeable bit better)
- price: $750 for the 64GB version. Not a big deal if you're OK spending flagship money, but the midrange has gotten crazy good this year (Nexus 6P, Moto Pure)