My phone history is as follows:
3G
4S
5
6
SE
8
The 6 was previously my favorite and was the first phone I thought about keeping for 3 years, but that has definitely been surpassed by my 8. I'm 3 months in with my launch day 8 and it is the best phone I've ever had, hands down. The form factor doesn't feel old to me (coming off the SE, may feel different coming off the 6 but it feels fresh again), and it feels so much more substantial and refined than the 6. Glass back is gorgeous, and the wireless charging is so convenient.
I do however have two gripes -
1) The proximity sensor can be really slow to respond when I pull the phone away from my ear (has done this across all software versions since launch day, could be my edge to edge protector but I really don't think so since it's perfectly aligned).
2) Battery seems to disappear. I'm a pretty light user and it has never been uncommon for me to take it off the charger in the morning at 6:30 and still be north of 85% by 11 PM that night. However with this phone I seem to be consistently in the 50-80% range by that time, and sometimes even lower. Sans screen brightness which I've generally kept on max on all iPhones, I have all my other settings managed for maximum battery life (location services only when using certain apps, minimum notifications, etc.). Yet for some reason the battery just doesn't seem to last as good as it has on other phones. Still good, just not outstanding like prior iPhones. This has also been pretty constant across all software iterations.
My battery is very healthy with a capacity of 1800 out of a max of 1821 mAh, according to that Battery Life app (98.8% capacity). Note however that Coconut battery indicates the design capacity is 1810 instead of 1821, and that my phone's capacity is only 1766 mAh (97.6%). Not sure why there's a discrepancy between those two apps.
So how is your 8/8+ and what are your praises/complaints?