It depends on who you talk to. I had a buddy that went through The Bulge. His experience was the same as Cut N Run's relative. However, I remember this talk going on the 24hourcampfire.com a while back; the experience was split evenly. Carbines were often times preferred in the jungle in the PTO and in urban fighting in the ETO.
30 Carbine will take a deer, but it's not an ideal round. I have one friend that hunted with it. Deer walked up to him at 10 yards. Bang. Flop. That was it. It's a 110 grain bullet and it's traveling around 2000 fps. At bow/treestand distances, it would be okay. It's just there is a whole lot better out there. The thing is that, at the muzzle, it's carrying under 1000 ft/lbs of energy. The rule of thumb is that a round ceases to be an effective hunting round when it falls below 1000 ft/lbs of energy. Just as a comparison, my rather anemic downloaded 308 WIN deer load falls below the 1000 ft/lbs threshold somewhere after 450 yards.
5.56 is definitely a step up from 30 Carbine, both as a military round and (as 223 REM) a deer killer. .223 Rem now has a small but faithful following among deer hunters. I've been kicking around the idea of using it for about 10 years, but never actually gone and done it. When I look at my current deer battery (30-06, 308 WIN, 35 REM, etc.) it seems silly to be thinking about it.
My one and only 30 Carbine story: We were all out shooting at our local range. One of the nice things about our club was that it had a full-auto range. It was nothing more than a stand-at table, a creek ,and a muddy slope about 20 yards away on the other side. You put milk jugs in the mud and had fun. So we were out there with a nice assortment of stuff and one buddy put a carbine in my hand and had me shoot a clip. There were 3 of us standing at the table. We'd just put out some milk jugs. I loaded a magazine and went hot.
I don't remember any sound. All I remember was this wall of mud suddenly rising up from the other side of the creek and coming at me. Lord only knows what somebody had left in that hillside for me to hit. The wall of mud hit the front of the table, then us, then continued on back another 10 yards and fell on the hood of my buddy's white Eldorado. Behind where we were standing were perfect silhouettes of us in mud.
"Dang!" Said my one friend, taking off his mud-covered glasses. "What was in those loads?"