A bit of an update and thoughts:
Battery Life: no problems, and no changes as far as how fast it is being used up as compared to before.
Edge Browser: Much, MUCH snappier as compared to IE on my Lumia 640.
Subtle Changes I noticed immediately:I really like the way when I now press the Phone icon, I can have it set to go directly to the dialer rather as before it would bring up my call history. I like the transparency of the lock screen, and once again I'll mention the speed of the new browser as compared to before.
Stability: My experience so far has been very good to say the least, I really feel fortunate, I DO RECOMMEND that you leave your phone plugged in to the charger when the update is happening (even if you have a full battery), coming from a PC tech with decades of experience, you want the phones processor to be running on all 12 cylinders when the change is happening.
I will keep updating my experience daily, but so far i have found no bugs in as far how I use the phone.
I opted to install the FAST preview option.