To be fair though, it's vastly closer than anything else around. You can get shell access—and it's a bourne shell, with environment variables, piping, control-structures, etc (it even has emacs-style command-line editing!)—add a C compiler, etc, on an unrooted Android phone.
It's not really Linux the way we usually know it (just the non-standard filesystem layout ensures that), but typing "cat /proc/meminfo" into a shell and seeing the expected result, and using ls, printenv, df, etc, to explore, really makes it feel pretty familiar to someone used to Linux or other unix-style systems. [It also seems to use the standard linux/unix group mechanism for granting app permissions: if you type "id" to the shell, you'll see the permissions the terminal app holds listed as groups it belongs to.]
The end result is that it really does feel like "Linux with a twist" rather than something alien.
It's not really Linux the way we usually know it (just the non-standard filesystem layout ensures that), but typing "cat /proc/meminfo" into a shell and seeing the expected result, and using ls, printenv, df, etc, to explore, really makes it feel pretty familiar to someone used to Linux or other unix-style systems. [It also seems to use the standard linux/unix group mechanism for granting app permissions: if you type "id" to the shell, you'll see the permissions the terminal app holds listed as groups it belongs to.]
The end result is that it really does feel like "Linux with a twist" rather than something alien.