I must admit, I am seriously stunned by some of the comments being left here by some people who seemingly feel perfectly OK in passing the buck on to Apple for this, when in fact they are to blame for some of their problems, allow me to elaborate...
As an OS X ACSP in-training, the FIRST thing we're always taught is BACKUP, BACKUP, BACKUP your data before you do ANYTHING to ANY device, in case something should good astray, which it often does, regardless if Apple made it or not. Remember, all Apple products are made by human beings, with flaws and deficiencies, and thus the products are not infallible and can also suffer from deficiencies.
To the people here blaming everyone but themselves for not doing a backup, which Apple has made so easy with iCloud backup on iOS, all I have to say is, tough. I have no sympathy of people who don't backup their data and then go whining and crying about it, and blaming the manufacturer. An update can have issues due to the myriad of configurations and installed content on a device, so things can go wrong. And please don't throw up the "but Apple makes and controls both hardware and software" crap. That only goes so far. With a platform that has over 500 million users and devices, there's bound to be some scenarios that Apple cannot anticipate, and will run into difficulties, and thus reiterating my point of doing regular backups!
To those complaining that Apple didn't test this update nearly enough, seriously, you just need to keep those kinds of mindless comments to yourself. I just skimmed all the major Apple and even non-Apple tech blogs, and NO WHERE is this being reported as a major issue. In fact, most people commenting on those blogs are overwhelmingly reporting complete success and improvements with the 7.1.2 update. While I'm not discounting the fact there is a small issue with the update for a very small number of users (myself being one of them), this does not appear to be as wide spread as some of you are making it out to be, so please just stop spreading FUD.
And finally, addressing those who haven't fixed your home button, I again say, tough. I have a lady at my workplace, where I am a Sys Admin, who constantly keeps coming to me with problems with her iPhone 4S, because she refuses to replace the power button. Each time I tell her, "this wouldn't have been an issue if you just fixed the button", to which she always responds "OK, I'll do it later, but for now can you just fix it?" I even offered to perform the repair, saving her a ton of $, and she still procrastinates. I finally told her NO, I won't be doing any more fixes, and she got so upset with me, I just told her you're wasting my time, and the resources of my department, by not taking our advice, and even free labour, so we will no longer be helping you.
People, BACKUP YOUR DEVICES, and FIX THE POWER BUTTON. If your button is broken, or the device hasn't been backed up, very simple, DON'T UPDATE IT! And if you're in a rush to go to work, or somewhere important, common sense kicks in here, and should tell you not to muck around with your device at this time!