I had the Frontier for a month until last week, but have gone back to my Huawei Watch.
I really like the HW, but the Frontier looked amazing, and I was intrigued by Tizen and the rotating bezel. I also love BIG watches. But, in the end, it just didn't fit my needs as well as Android Wear. The bezel is great, but I can do so much more 'hands-free' with AW - and when it's chucking it down, and I'm walking my son home from the childminder in a buggy, and I want to check/dismiss/look at messages without needing to stop and scroll about or push buttons, the Gear S3 just couldn't cut it like the HW.
I was also a little handicapped by not having a Sammy phone, so I couldn't dictate a text (only works with Samsung Handsets, it seems, which is a bit 'Apple' of them), the UK still doesn't have Samsung pay, nor does it have the LTE variant.
It's a shame, as the form factor was perfect, and I much prefer the actual UI, but only if I'm sitting at home and scrolling about. Out and about, when a smartwatch really comes into it's own for me, the S3 just couldn't live with Android Wear.
And that's before I mention the dearth of apps...