This topic has been beaten to death, especially in the hunting section.
Having taken over a hundred deer with .22cf, I can give you some guidance on bullet selection.
With the .223, any of the 55gr or heavier soft-point bullets will do well. My favorites are the 60gr Hornady PtSpt, and Sierra 65gr "GameKing". These both compare favorably with the 80-100gr bullets from the .243. If you don't reload, the 64gr Winchester load and the 60gr Hornady "Custom" loads have enviable reputations in my neck of the woods (W.Georgia).
Avoid the "plastic tip", "Blitz", "TNT", "SX" and such bullets. Any hollow-point is also suspect when it comes to light game use with the .22cf's. I handload and particularily like the Sierra 63gr SemiPt, and 65gr GameKings. However, my .22-250 has a 1/14" twist and it will shoot the 63gr "ok", but key-holes the GameKings. I bought a bulk quantity of the 60gr Hornady "Blems", so it's my current "in-use" bullet for deer. I've never recovered but one of the Hornady's, it was as raking chest shot on a ~120lb doe at ~35yds. Bullet was recovered just under the hide on far side (~18" of penetration) and weighs 38.5gr with perfect mushroom. Was fired from an AR15 w/16.5" bbl at ~2,800fps m/v. Deer bolted and ran ~30yds and collapsed. Or, about like a similar shot from a .30/30. Typical performance....
Just as with any cartridge, the three most important factors in hunting are shot placement, shot placement, shot placement.
fwiw; I've lost more deer using the .243 than any other caliber/cartridge. Thats because I've typically been less distinguishing on my shot placement expecting the 100gr bullets to "do their job". Sometimes they didn't....
Most .223's are notably accurate and as such allow careful shot placement. Lack of recoil adds to the equation. Use it if it's legal and you're comfortable with it.
Most nay-sayers have little or no experience with it.