Here's the real truth:
1. For most repairs, Apple mails off your device to a service center. While many people can live without an iPad, or MacBook, most people are tethered to their phones. They know this, which is where their real genius shines: IN SELLING DEVICES. Sure, your iPhone is only a year old and is running slow because it needs a $30 battery, but who wants to be phoneless for 5 days? The average customer isn't going to be as savvy to transfer their sim card into an old phone or a Walmart phone and Apple will take this opportunity to sell you an upgrade.
2. Now, out of warranty repairs are expensive but even if you are under warranty, they will give you the runaround. At your appointment, if the genius takes your computer into the back room, he's trying find reasons to charge you money. The only reason they open your device is to check to see if these little paper dots have any moisture. I've also heard of people bringing in their Mac for hard drive replacement, but was told it would cost $800 because they had a hairline crack on the screen. In other words, Apple will sell you repairs that have nothing to do with the functionality of the device. They're not stupid, they know by quoting you astronomical prices, while you're inside the Apple Store surrounded by magical devices, that you're more prone to buy a new one. If a splash of water gets on on your keyboard and a few keys won't type... Apple calls that a "LEVEL III HARDWARE REPAIR" and will want to charge you up to $1,500.
3. As far as quality of the repairs at the service center, they are top notch. So if you're still under Apple's free 1-year warranty and the genius says you're clear from water damage and hairline cracks, they are going to want to refurbish everything so make sure you're data is backed up because they often erase or replace hard drives. The technicians at the service centers are certified experts and the only people who really "mess up" devices are the geniuses at the Apple Store. When the store is slammed and they're in a hurry, they might forget to put all the screws back in or misaligned the screen, or drop your device while it's the back room. I've seen it with my own eyes and I wouldn't trust the geniuses with a mouse.
4. There are affordable Apple specialists out there who have previously worked for Apple and opened their own business. For devices that are over 1-year old, they can be 30-50% cheaper than the Apple Store and you can just walk in when you have a problem. No waiting in lines or mailing things off for weeks. But do your research and stay far away from gas stations and clothing stores that have signs that read "WE FIX IPHONES". Places like In & Out repair and ibreak-uFix are the cheapest because they use the cheapest parts and they ARE NOT GENUINE APPLE CERTIFIED. A place that fixes Android and Samsong isn't going to take pride in the craftsmanship of Apple Products will put generic parts into your device. But if you want to save a whole $10 by getting your screen replaced at a store that buys gold and sells used grillz, don't say I didn't warn you. Don't be cheap, because you'll get what you pay for.