From these two threads,
LONG is archaic an
Use CLOBs. One limitation of LONG is that LONGs can't be handled correctly from SQL - PL/SQL.
For a more detailed description of the differences, see http://www.comp.dit.ie/btierney/oracle11gdoc/appdev.111/b28393/adlob_tables.htm#insertedID2
If Oracle says a feature is deprecated it may not be available any longer in a future release. So unless your application will run on the current Oracle version for an unlimited amount of time, don't use deprecated functionality.