Almost every mobile OS some closed source components, it is an inevitability at this point. Even though BB10 is closed source it is not however a "Walled Garden" in any sense of word and application sideloading is available without any hacking, so you are not limited to approved app sources. Rooting or other forms of hacking is possible as shown by the Playbook, but given the small and business oriented user base of Blackberry 10 users there is probably little desire for rooting or other forms of hacking. Having hacking or rooting is a matter of having a user base that desires it. What really makes Blackberry 10 unique is its architecture, it is based on QNX and is highly optimized. BB10 also has a nice ui and features like true multitasking.