I had my phone for almost a year and a half without cracking it. I've dropped it a few times and gotten lucky, but without a case or a screen protector, it was bound to happen eventually. I took a road trip 2 weeks ago and shattered the display.
The repair was relatively simply: just take out some screws and unplug some cables. I stripped a screw on the cable bracket when I opened the phone; no big deal, I just bent it out of the way. Disconnected the 3 cables, then stripped one of the screws on the home button assembly (I managed to get it out using a rubber band between the screw and the driver). Other than that, the installation went smoothly and all of the parts functioned as expected. Earpiece speaker is loud and clear and the front camera is great compared to how it looked before. Overall, I'm very pleased.
First and foremost, put a quality case on your phone so that you don't have to make this costly repair. If you do have to, make sure you keep track of your screws and don't mix them up, especially for the cable bracket. Be careful not to over-strip the screws; if you think you stripped a screw, get a rubber band and try to get it out that way. Have patience and don't rush or you will risk ruining your device.