Maybe I drank too much Kool Aid, but there isn't much I would change about the Glock. The grip angle is different, but I am not convinced that is a bad thing, and at any rate, all it means as near as I can tell is that you hit a couple inches higher. That is a training issue, if you call it an issue at all. The grip can be bulky. My G20 is no small pistol. But I've seen a 100 pound 16 year old girl shoot it well enough that I have difficulty seeing what all the hub-bub is about. The trigger reach isn't as bad as most DA autos, either. So I call this a personal problem, more than anything. If the Glock fits you, there really aren't many (if any) better choices for an all around defensive handgun.
KBs? Unsupported chamber? Bullpucky. The Glock's chamber still offers roughly the same support as many of the older 1911s on the market. It is still within SAAMI spec, and perfectly safe to shoot with all SAAMI spec ammo, provided you adhere to at least the manufacture's recommendation not to shoot un-jacketed ammunition through it. And for $100 or so you can drop in an aftermarket, conventionally rifled barrel and worry not even about that. The only reason I dropped a KKM Precision in my Glock 20 was because I started handloading for it, and while the chamber being on the looser slide of SAAMI specs makes it very reliable and tolerant of a wide variety of ammunition, it also accelerates case wear. The only reasons to buy an aftermarket barrel for your Glock are as follows:
+Better case life if you reload
+Safer shooting un-jacketed ammunition
+Caliber conversion
You might get better accuracy, but for most applications, this won't be necessary and in fact, a lot of people won't even be able to shoot their Glocks well enough under duress to take advantage of any accuracy advantage anyways. However, if you're one who can and you want this accuracy, add that to the list as well.
And don't even get me started on kBs. I don't even worry about them.
That's about all the con's I can think of. Now consider the pro's:
+Reliability. Sure, they fail like everything else. But they seem to fail less than most. The Glock has become the standard by which all others are judged. It is like the AK. Shoot it hot, shoot it dry. Shoot it covered in ice. Shoot it over and over again until your finger falls off and the cows come home. Shoot it until pallets of ammo have been reduced to noise and brass. The Glock keeps on working. People were initially skeptical of Gaston's plastic pistol until he proved you could rely on it to save your life. His success in doing so is evident by the overwhelming popularity of these pistols in the law enforcement and civilian defense marketplace, as well as in foreign military and counter-terrorist organizations.
+Durability--we've seem them shot out of cannons, dropped out of airplanes, dragged behind cars, shot with other firearms, and generally just abused in the most obnoxious ways possible. The Glock is probably responsible for starting the "Torture Test Craze." What does it prove? That Glock can take a lot of abuse.
+Lightweight with good capacity. My Glock 20 gives me 15+1 capacity of full power 10mm Auto. That is like having three .357 Magnums! It's a platform with roughly the same dimensions and weight as a loaded 1911, but with at least twice the firepower.
+Very good defensive weapon trigger. The trigger pull comes in between 5 and 6 pounds, stock, from most accounts. It is relatively short with only a tolerable amount of take up and grit. What's better? The trigger pull is the same every time, and has one of the shortest and most distinct resets available.
+SIMPLE! From its design to its operation, the Glock embodies the spirit of simplicity. It has relatively few parts--in the neighborhood of 33, most, if not all of which are interchangeable between at least pistols of the same model. This is less parts to break at inopportune moments. Less parts to fail. Less parts for armorers to keep stocked, and replace. Detail stripping the pistol is like playing with Legos, and there is not a part on my Glock I don't feel confident that I could replace if it broke. I have some experience with a lot of autos, but the Glock is the only one I can say that about. And it's a point and click interface. Not only do you not have to memorize and train for two separate trigger pulls like many of the DA autos on the market, you don't really even have to train to remove an active safety. All you have to do is train to keep you trigger out of the trigger guard, and getting that front sight center mass before you squeeze. Simple. I like that. Keep it simple, silly.
+Control--love it or hate it, the steeper grip angle does allow for a very good level of control. Add to this one of the lowest bore axises on the market, a little bit of flex in the frame, and a wide grip that helps distribute recoil and shock forces over a larger part of the hand, then add that to a relatively light trigger pull with a very short reset, and you have a pistol that works with you to help get rounds on target quickly.
+Modularity and aftermarket support. Only the 1911 can claim among all other centerfire autoloading handguns to have as much or more aftermarket support than the Glock. From your choice of sights, to trigger options, and just about everything else, the Glock has an amazing array of choices. This combined with the amount of interchangeability and modularity the platform offers gives you options and flexibility that most just don't have. Swapping out barrels for caliber conversions and being able to use pretty much all magazines of the same caliber in any Glock chambered for that caliber, regardless of frame size or slide length is just the beginning. Take a look at LoneWolf Dist and consider the plethora of different slides available, check out the growing array of custom gun makers marketing grip sculpting, as well as the alloy frames becoming available. Possibilities are endless.
+Price. In a market where performance is supposed to have a price, the Glock gives you a lot of performance for relatively little price. There may be better deals out there, sure. But the Glock does a good job of providing proven, reliable firepower at a price that the common, working man can afford. Power to the people? Heck yeah!
While we're on the subject, let's have a candid conversation about GLOCK magazines. Specifically, taking them apart. Disassembling your magazines from time to time in order to clean them is a smart thing to do, especially if you shoot outside and train on things like mag changes where you might drop one on the ground. Glock magazines are some of the most difficult magazines to take apart I have ever encountered. Not only do they have the little push-button on the floor-plate, like most other manufacturers, but the floor-plate is also held in place by little notches on both sides, preventing it from sliding off, even when the button is depressed. You have to actually crush the body of the magazine in order to warp it out of shape, just to slide the floor-plate off. It is honestly one of the stupidest ideas I have ever seen.
It takes a little force, but lets consider some things.
First off, the weak link to any autoloading firearm is usually the mags. Lots of different firearms have been hindered by flimsy, unreliable magazines. Consider the Beretta M9 and the M16/AR-15. Today, magazine selection has improved for both of these models, but in the past, this wasn't always so. Weak springs, poorly designed followers, and shoddy, flimsy craftsmanship that allowed the magazines to dent easily can turn a functional firearm into a paperweight very quickly.
Second, most on the frontlines, whether they be police officers on the streets, or soldiers on a battlefield, probably don't clean their magazines much. If a magazine becomes lost, dirty, or damaged, it is more likely that they are just going to turn the defective magazine into the armorer, who is either going to fix or replace it.
What Glock has done is create a simple, durable, reliable magazine with decent capacity--one that can take abuse--but which is cheap enough to replace if actually broken. If they had went the other way and not designed their magazines to be as durable as the rest of the platform, then there would be all sorts of complaints about the lack of reliability/durability, ect. You can't please everybody, but erring on the side of caution by ensuring, if nothing else, the reliability of the pistol and its magazines is a pretty good place to start.
Armorers can deal with the magazines easy enough. The troops mostly just care that the pistol fires when they pull the trigger.
I know I only clean my mags once in a blue moon. So if I have to put a lil bit of elbow grease into popping off my floorplate, that fine with me. At least I know it's not going to pop off at a less opportune time, and at least I know the magazine is going to be durable enough to take hard use. That is far more important to me. And Glock manages to keep these mags readily available, even to non-military/LEO customers, for around $20 to $25. Compared to lots of magazines out there running $40 to $50, many of which aren't as durable or reliable as the Glock's, I think Glock got the important things right. I'm fine with the Glock magazines.