I've been having problems syncing my iPhone 4S with iTunes for at least a year, spending a minimum of an hour each time (waiting for sync to start, transferring purchases even though I clicked NO in the popup, waiting for changes to be applied, deleting apps I didn't ask to be installed, starting over, waiting some more, etc). I also appear to have some corrupted data and have jumped through the erase/restore hoops, to no avail. (The corruption, I'm guessing, is likely due to my yanking the cable in frustration, either while endlessly "waiting for changes to be applied" or when it "finishes" syncing, yet won't let you eject because it's still syncing!) Because of this mess and iTunes' obsessive need to transfer purchases, I rarely sync.
Knowing Apple's lockdown mentality I didn't expect to find anything to help, but gave this app a try and was very pleased to find that it does most of what I want, and more. The part that grabbed me is being able to extract and save an app and data as a single file, or just the app (but unfortunately not data alone). If for no other reason, this makes iOS OTA updates needing GBs of free space much easier. I just confirmed this with the 8.1.1 update - I extracted a video app with about 3GB of data, deleted the app and data from the ipad, updated to 8.1.1, then restored the app and data. Not only did it restore everything, but also into the same folder, in the same location! I first tested this with some apps that had data I didn't care about losing and it worked each time. A few days ago I updated Penultimate, but found I prefer the older version so I restored the old one with its data (the new version converts data so that it's unusable in the older one).
iMazing also lets me install older apps that I want to revisit without having to spend an hour+ with iTunes. I haven't, however, done anything yet with music so I can't comment on that yet.
The thing I would like to see is being able to restore an app's data from backup if it wasn't separately extracted. In my Penultimate example, I first updated via the App Store, only to find that when I tried to revert the data had been converted. Not having Dropbox backup enabled, my only option, from what I could tell, was to do a full ipad restore. Fortunately, I have an older ipad that has the old app and current data so I extracted the whole thing, then restored it to the newer ipad. Worked beautifully. The whole process took only a few minutes.
As for iMazing phoning home, I have to echo others' comments about blocking Google Analytics (and anything else Google) because I have zero trust in them. Even if it weren't Google, I don't like being monitored - whether or not it's as innocuous as how often an app is launched or what features are used. That kind of monitoring is apparently too tempting for some developers not to abuse (I'm not suggesting that this developer is abusing anything, but some have).
Overall, I'm very pleased with iMazing for getting me out of iTunes Hell.