lot of people are unhappy with JB just rolled out for tab2. the ICS for Tab2 has a batter interface then JB and lot of people planning to downgrade the OS back to ICS.
there is no big difference in either of the releases apart from few new features and the UI changes done by samsung in the touch wiz.
if you are set to buy tab2 to go for it, you will get the taste of ICS and JB will arrive eventually.
Give me some MB's http://db.tt/IzxPvtOl
Samsung galaxy S3 GT-I9300 Running Stock Jelly Bean 4.1.2