After frontend submission in non-trusted mode, there is no admin notification of new submission, yet the article remains unpublished until approved by admin. This means admin needs to constantly be checking.
There is a coomets feature but, again, no admin notification of new comments
There is no way to limit the number of characters in textarea fields.
There is no way to submit a gallery in the frontend, even in trusted mode.
I know ZOO is currently under consideration for JED Editor's Pick, but I can honestly say that the current limitations should preclude it. In my opinion, ZOO was rushed into stable production in a cynical attempt to sell the companion Apps bundle, but truly, there are many features missing which are core to many other CCKs.