It mystifies me that anyone complains about iTunes being frustrating. It has worked far better for me in putting exactly what I want on the devices I have that support it than anything else I've tried. The only thing I've tried that even approaches it is Winamp, and I'm pretty sure you can use Winamp with iDevices too. But why would you want to use something that is just like iTunes but not as intuitive when you could use iTunes?
You've had a good experience with iTunes because you took the time to set it up. I've used iTunes a handful of times, either to sync files with friends' mp3 players a few years back, or more recently, to transfer music files onto my roommate's iPod. Well, that file transfer was a snap; one click, let 'er rip. But when I browse the music on that iPod, 90% of the albums have the tracks in random order as opposed to arranged sequentially. These are albums that I personally ripped from my collection of CDs, and they worked like a charm the first time on my Galaxy S3 with a simple copy/paste, but apparently iTunes has determined that it knows better than Pink Floyd what order people want to listen to "The Wall" in. That's frustrating, and I don't want to take the time to clear the entire contents, figure out why it did that, configure iTunes so it won't do that, and redo the process from scratch. No other music software I've ever used has randomly changed the order of files that have proper ID3 tags and file structure. What the hell iTunes?
If you like iTunes, more power to you. But judging from the responses on here, more people are of the frame of mind that I am; it's annoying, bloated software, and even if it can make things easier, it's not the best for sorting a music library, and the fact that you have literally no other option for getting music onto an iPhone/iPod is frustrating.