First: there's a really big difference between hate, and preference.
It has low recoil (for better controllability), it is a NATO round (which means it will almost never be in short supply), and it offers high capacity in a small size. Additionally, it is cheaper than almost any other alternatives (which means it is easier on your wallet for practice). Personally, I can shoot several 9mm's in the time it takes to shoot a few .45's.
Also, 9mm guns tend to be much lighter than .45 counterparts, examples being Glock and 1911 pistols. This makes them easier and more comfortable to carry.
You're comparing apples and oranges. The 1911 is all metal while the Glock is mostly much lighter polymer. A metal 9mm like my Walther weighs more than my .40 cal. So by your logic I can say that my .40 is the better carry weapon.
The problem I have with new Glocks has nothing to do with weight, and everything to do with ergonomics. The one-size-fits-none grip of the Glock simply doesn't feel right in my hand. The finger groves molded into the polymer are made for someone about half my size, and I just can't see paying that much for a pistol that doesn't feel good to shoot, and I have no time or patience for reworking the thing. That's why I bought my S&W.
Not to turn this into an I hate Glock thread, I think they make fine weapons and I would buy a used first generation Glock if I could find one.
As for availability of ammo, I've never had a problem finding 9mm, .45 acp, or .40 S&W. I don't believe in SHTF, day-after nonsense, so I don't think I'll be reduced to scavenging any time soon, but if that happened who do think would have the ammo for your 9mm? That's right, you'd have to take it away from a bunch of cranky military types and police officers. Personally, I'd rather take my S&W .40 and hide in a cave somewhere until it's safe to come out.
As for usefulness in a combat situation, the 9mm is much easier to shoot while under pressure than a larger .40 or .45. The speed and accuracy at which you can shoot a 9mm easily makes up for the (small) ft-lbs energy difference.
And, you've tested this how?
I've been in combat with nothing but a pistol in my hand, and I can tell you that I want all of the power I can get, especially if the other guy has a long gun, or a MG.
As for speed and accuracy, that's simply a matter of practice. I'll put my 15 round, or as some like to call it, my 14 +1, S&W against a 9mm any day. I shoot fast, and I get consistent tight groups at 25 - 50 yards. I did the same when I carried a 1911 (old school army). Actually, the same goes for any pistol I've carried including my .38spl, 45LC and .44mag revolvers. You put the time in at the range and pay attention to what you're doing and you'll shoot just fine with anything you decide to carry.
If there are any critical problems with 9mm, please tell me. I just want to know what's the deal with people disliking 9mm.
Nope, no critical problems. Like I said, it's a matter of preference, not hatred. I like the 9mm just fine. I have a really nice antique 9mm that I still take to the range, and if a good deal on a modern 9mm came along I would take it. I might even carry it occasionally.
The 9mm has plenty of penetrating power. In fact, in most ballistics tests I've seen it penetrates better then either .45 or .40. However, the heavier, bigger rounds of the .45 and .40, in my opinion - your mileage may vary - simply have a little more knock down power, and are less likely to travel through the body of your target and injure an innocent party down the street.
I've seen what both the 9mm and .45 acp can do to a man at relatively close range, and based on personal experience I chose the bigger caliber.
