not much I can add about it except what I have experienced with in through the years
My expierience with the 223 started in jan. of 1978, I purchased a new rem. 788 package rifle chambered in 223, the glass suk'd so I installed a Charles Daily 4x12x44 on it (back then good glass was impossible on my budget)
that rifle taught me more than I could ever learn reading books, I also sprung for a lyman reloading kit so my supply of ammo was pretty much unlimited long as I had work. that summer me and that rifle accounted for 193 groundhogs, back then I had it figured out and knew it all, late in the summer I started getting calls from farmers to help fill damage permits, I think I killed 58 deer for the various farmers I helped out, and was amazed that they would pay me for shooting deer.
through the years that rifle accounted for many, many deer, more than a few fall turkeys, and literaly thousands of groundhogs, crows, even blackbirds, that old ugly gal would shoot well.
As the years went on I put the old girl away and moved on to better longer range stuff, so I thought, used a 243 for years but thats another thread.
about 1985 I purchased a ruger mini 14, it was my doe season rifle, didn't take long to figure out the heavier bullets notably the 64 gr win power point would make short work of deer, I began to put togather the conclusion that you need the proper bullet in a 22 cal centerfire if you want to deer hunt, or wait for the perfect sunday morning broadside, onside front leg foreward shot.
I do and always will have a 223 in my safe, today I have 5, it was 8 till I sold one to a cousin, one to a friend, and gave one to a nephew for his high school graduation.
I reloaded for the 223 for years, its an easy cartridge to load, there is tons of data on the net, and components are fairly cheap and easy to find, let me just say the bulk of my loading was 55 gr stuff, with a bit of the heavier deer bullets thrown in, and my choice of powder was IMR 3031, H335, and IMR 4198.
for what its intended for the 223 has no peers, it will work on all game from squirrels to deer if you do your homework and use the proper components.
Today all I shoot in the 223 is Ultramax reman ammo, mostly 55 gr hornady sp's, it shoots well and performance is excellant. it does this in my factory RRA 8 twist varminter

folks either love or hate the 223, think those that hate it have never given it a fair chance
RR
in the 90's I bought my first AR chambered in 5.56, that's a completely different thread so will get to it later.