...are all true. Linux cannot be compared to OS X or even Windows, for elegance and ease of use for the average end user. I would not however says its not a good product. Linux runs the internet. Android is the only competeing OS for mobile platforms, and its Linux. ChromeOS is Linux. Where it sucks is the desktop. Some distros, notably Linux Mint, are fast approaching Mac OS X and Windows both in elegance and ease of use. Lion and Mountain Lion have been, in my humble opinion, regressions for the OS X platform. Tiger was a peak for OS X, Leopard close to Tiger, one of the reasons I stay PPC. Windows 7 and 8 have been vast improvements for Windows, at least compared to Vista, but XP will be the standard Windows will always be measured against.
Why does Linux suck on the desktop? One reason is its highly, highly fractured. Imagine one meta Linux, worked on by everyone who loves Linux, combining the very best of all distros. It would be free. It would rule the world. That is Linux on the server side. Most end users do not want to install an OS. Most end users do not want to open a commandline, ever. Most want what Apple gives them, easy installs, updates, swipes and gestures, point and click. Which is fine, but with Linux you have to be prepared to get into the guts of it and edit a config file every now and again. You have to be comfortable with the commandline. You have to accept you might screw things up royally by adding a # somewhere where it shouldn't be.
All of those issues are magnified on PPC, due to the small user base. So again, rjcalifornia is totally accurate in his assesment. But it is still the only option other than Microsofts and Apples expensive walled gardens.
Linux is now and will be for the foreseeable future a hacker/nerd OS. Which is also how most Linux users like it.