K2 is fantastic Tool for developing website, i loved it !
i would like to make some suggestion, after searching through many internet and forum i have found that following discussed FUNCTIONS NEEDS TO BE ADDED

1 FRONT END EDITING
when user submit the post they should only see those categories which are Assign, the hierarchy of categories should not be shown, if its shown its make confusion to blogger !

2 FRONT END LAYOUT and Acess level
the Front end access level (public, register, special) should be hidden all the time, only certain access level should be shown which is allowed to user group, for this K2 may need to develop more powerful user group system
the drawback for current system is that if admin create additional access level for there own team, its also shown to frontend user during post which makes confusion

3 PMS
it will be excellent it fronted user has Personal Message System in K2 bloggin

4 Registration Process
During Registration the visitor should have right to assign them to specific user group which are visible to fronted, and automatically permission assign when they click on the specific user group during registration, currently we have to assign a specific user group to registered user