5. Knox: The evil of user freedom evils
Something is eerily NSA-like here. Not only are the bootloaders in Samsung devices hellishly locked down to the point where even Towelroot won't work in some cases, but there's this little switch, called a "qFuse", that spies on the phone's system partition, Big Brother style, and threatens to void the manufacturer's warranty on the device if it detects even the slightest degree of modification (removing #4, for instance). This is especially problematic for registered Android developers like me: merely testing apps is enough to trip it, and oh, yeah, it pretty much guarantees a hellishly evil ride for anyone trying to break out of the TouchWiz cyberprison.
4. Bloatware, bloatware everywhere!
This tends to be both an AT&T problem and a Samsung problem, but it's still a problem regardless. The amount of disk space for me, a registered developer, mind you, with developer needs, to use to develop and/or test apps is crucial. More disk space used up by Samsung and AT&T bloat means less disk space available to me, the developer, and the amount of running system processes adds to the burden by slowing the phone down and taking away precious testing time due to the latency. Android in general isn't an issue with this, but when Samsung and AT&T start adding on their own stuff on top of Google's and preventing that stuff's removal, wasting precious disk space in the process, the problematic details really add up. And apps that are "disabled" aren't uninstalled either. No, they're simply disabled, which means no, they won't function, however, they still waste precious disk space regardless.
3. Launchers Don't Change Everything
You may ask, 'Why not just install the Google Now Launcher on a Samsung device?' Because the launcher is only the home screen. What about the notification shade? The system/status icons? They all remain the same regardless of what launcher the user has installed, and moreover, they take up precious space on disk besides. Not to mention #2, due to the fact that Knox, among other serious barriers, prevents the user (or developer) from removing the old launcher once the new launcher is installed.
2. Multiple preinstalled apps that accomplish the same task
The KISS principle is seriously being violated by Samsung with this one. Simplicity is essential to the overall usability of a device. By attempting to copy Apple in every which way, what Samsung has done instead is made Android even more complicated than it needs to be. Take, for example, S Voice. Wait, S Voice still exists despite the fact that Google Now is the standard?!?! Yup. That means two virtual assistants, S Voice and Google Now, both preinstalled on the same device, creating an unnecessary duplication of a feature ― Google Now ― that the duplication in question should have just been ditched in favor of from the get-go. Another example is the Samsung Account. If I am prompted to sign into Google, why should I also be prompted to create or sign into an account with Samsung as well? It makes the device setup process even more hellishly convoluted than the setup process for (pardon me while I take a break to cringe at the word) Windows! And the fact that I'm typing this on a Chromebook sure says a whole lot about how I feel with regards to THAT operating system.
1. A user interface that complicates and bogs down performance
A comment I hear quite often from Apple zealots with regards to Android is the complaint, from personal experience with a device that isn't pure Google, that Android is "slow". And when it comes to Samsung in particular, man, are they right! Because of everything Google, Samsung, and AT&T, instead of just Google in the case of pure Android, have all contributed and poured into the device's system, the result is a slow, painful user experience that's being strangled by the OS, eerily Vista-like. Instead of keeping it simple, they make it complex. Instead of keeping it unified, they make it convoluted, and the resulting software salad, the über-OS that got forked into oblivion instead of kept natural, is, quite literally, what I would call the OS from Hell.