Until SP 2010, the datasheet was quite useful but rudimentary. It was an ActiveX control that did not allow any alterations to be made. With 2013, Microsoft came up with a slightly (very slightly) better replacement called the Quick Edit.
Quick Edit uses HTML5, has a better layout and uses JSGrid to render the data. Check this post for details about that ( chuvash.eu/2014/11/27/jsgrid-basics/ ).
The author, Anatoly Mironov, has another post that explains how to lock a single field in the Quick Edit. ( http://chuvash.eu/2014/11/28/disabling-a-column-in-quick-edit/ ).
However, if you are like me and promised the client all sorts of functionality in the Quick Edit, read on.